Stem cell donor and recipient FAQs

A stem cell transplant is a stressful process, both for the patient and his or her loved ones. Many transplant centres have counselling resources to help the patient get through this difficult time. It may be useful to know what services are available. Don't hesitate to use these services - they exist for the benefit of the patient and his or her loved ones. 

Here is a list of frequently asked questions that may assist you – donor and recipient patient – through this process.



What are stem cells?

Stem cells, specifically blood stem cells, are found in bone marrow, peripheral circulating blood and umbilical cord blood. These blood cells are immature cells which can become: 

  • Red blood cells - cells that carry oxygen 
  • White blood cells – cells that fight infection 
  • Platelets – cells that help control bleeding. 

Our bodies are constantly manufacturing these cells in order to sustain life. Without these healthy cells, the consequences can be life-threatening. 

What is Bone Marrow?

Bone marrow is the soft tissue inside bones that produces these blood forming stem cells. When disease affects marrow, such that the bone marrow cannot produce the stem cells or produces diseased cells, a stem cell transplant may be your best treatment option.

How does a stem cell transplant work?

A stem cell transplant replaces the recipient patient’s unhealthy stem cells with the donor’s healthy stem cells. There are three sources of stem cells used in transplant. 

  • Bone marrow 
  • Peripheral (circulating) blood 
  • Umbilical cord blood. 

The choice of the type of stem cell donation will be a medical decision and will be made by your transplant physician and the transplant team. 

Some things your transplant team will take into consideration when deciding on what type of transplant you will receive include: 

  • Whether a genetically matched donor is available 
  • Your body size 
  • Your disease status 
  • Your diagnosis 
  • Your age 
  • The urgency of the transplant. 
How are donors matched to patients?

Stem cell matches are determined according to DNA markers called Human Leukocyte Antigens (HLA). These antigens are found on the white cells in your blood and are inherited from both your mother and father. Thus, a sibling can represent the best potential match. However, due to the random distribution of these antigens, most patients have approximately a 25 per cent chance of a sibling match; the rest rely on a volunteer donor from outside their family. 

When you register to join the Stem Cell and Marrow Network, a sample of your DNA is obtained to identify your human leukocyte antigens (HLA), which are recorded in our database for patient searches. HLAs are genetic markers in the proteins of white blood cells inherited from our parents. A number of antigens have been identified as important when matching donors and patients: the closer the match between patient and donor, the better the outcome. 

Some patients have many potential donors because they have inherited common antigens and their markers are inherited in a common combination of gene forms. These markers occur with varying frequency in different ethnic groups: those common in Caucasians, for example, may rarely be found in the Asian community, and vice versa. While not always the case, patients are more likely to find donors in their own ethnic communities, which makes a diverse donor base extremely important. 

Learn more about donor eligibility.

I need a stem cell transplant. Can my relatives be tested to see if one of them is a match for me?

Your transplant team is responsible for identifying any potential matches within your family and arranging for testing. In most cases, family testing focuses on your siblings. If you have questions about the possibility of a relative being your donor, we encourage you to have a discussion with your transplant team.

Note: It is not the responsibility of you or your family to find your donor. Your transplant team, working with the Stem Cells and Marrow Network is responsible for locating a matched, committed donor for you. Anyone who joins the Stem Cells and Marrow Network is making a commitment to be available for all patients in need. Once part of the network, their HLA typing will be included in searches for all patients, both in Canada and abroad.

How is a volunteer unrelated donor found?

Your transplant centre team identifies potential volunteer unrelated donors by submitting a search request to the Stem Cells and Marrow Network.  These potential donors will be contacted and undergo further testing. This process can take time. 

More about the donation process.

What is the Canadian Blood Services Stem Cell Registry?

The Canadian Blood Services Stem Cell Registry is a program dedicated to recruiting and finding healthy, committed volunteer donors for patients in need of stem cell transplants. Our staff coordinates searches in Canada, as well as other international registries, towards a single goal - helping patients get the stem cells they need.

Fewer than 25 per cent of patients who need stem cell transplants find a compatible donor in their own family. The rest rely on those who have volunteered to donate stem cells to anyone in need. The decision to begin a search for an unrelated donor, as well as choosing a suitable donor, rests entirely with the transplant centre. Our mandate is to coordinate the search and subsequent donation of an unrelated volunteer donor. These volunteer donors must meet a variety of eligibility requirements and undergo a comprehensive health assessment to ensure that the donation process will be safe for them and anyone receiving their stem cells.

Our Stem Cell Registry belongs to an international network of registries, we can search more than 36 million donors in more than 80 registries in other countries when we need to find a match. By making donor data available worldwide, international registries have significantly increased the odds of finding a matching donor for any patient anywhere in the world.

The Canadian Blood Services Stem Cell Registry operates according to international standards established by the World Marrow Donor Association (WMDA). The WMDA is the international organization that promotes the ethical, technical, medical and financial aspects of stem cell transplantation.

How are stem cells donated?

There are two types of donation procedures: a bone marrow donation or a peripheral blood stem cell donation. The determination of the procedure required is made by the transplant team. 

A bone marrow stem cell donation is a surgical procedure performed under anesthesia. Hollow needles withdraw stem cells from your bone marrow from the back of your pelvic bones. The amount of bone marrow collected ranges from 500 to 1,500 millilitres, depending on requirements of the transplant. This procedure lasts 45 to 90 minutes. Your marrow will replenish itself within four to six weeks. 

In a peripheral blood stem cell donation, your blood is drawn through a needle in a non-surgical procedure done at the hospital. After the stem cells are separated from the blood, the remaining blood components are returned to your body through another needle. To prepare you for your donation, you will receive daily under-the-skin injections of granulocyte colony stimulated factor (G-CSF) for five days before the donation to increase the number of blood stem cells in your bloodstream.  

In some cases, an umbilical cord blood transplant may be a third option to recipient patients.  

More about cord blood donation process.

I am a recipient patient. How are donated stem cells delivered to me?

Once the donation is complete, a stem cell courier who is trained in handling stem cell products will be on hand to carry the stem cells from the Collection Centre back to your Transplant Centre. The Stem Cell and Marrow Network ensures travel plans and documents are in order to safely travel in Canada and around the world. Umbilical cord blood units travel by medical couriers as the products must remain frozen.

Do donors ever say no?

The vast majority of people who register to donate stem cells have a strong commitment to help all patients in need of an unrelated stem cell transplant. When they are asked to donate, they usually respond positively and enthusiastically. It may be a few years between the time a person registers and the time he/she may be asked to donate. Thus, many factors may have changed in the interim, for example, issues with his/her own health. As a result, there is a rare chance that some people may decline to donate. Usually, this is identified early in the search process, when several potential donors may be under consideration.

Are there stem cell matches for every patient?

Are there stem cell matches for every patient?

Unfortunately, even with millions of potential donors listed on registries around the world, as well as many public cord blood units, it may not be possible to find a stem cell match for all patients. If a donor is not found, it may be that you have an unusual genetic marker/ antigen, or the combination of antigens is uncommon. In this case, your transplant team may consider other options for you and will discuss these options with you.

I received a stem cell transplant. Will I ever get to meet my donor?

The privacy of both the stem cell donor and recipient must be respected. For this reason, there are restrictions regarding the direct communication and exchange of identifying information between donor and recipient for at least one year, post donation.

After the year has passed, if both donor and recipient consent in writing, communication may be permitted. You should be aware that some transplant centres and international registries require a longer waiting period, and some registries and transplant centres do not permit direct communication between donor and recipient under any circumstances.

To determine if you would be able to have contact with your donor, please have a discussion with your transplant team.

How can my friends and family help?

The search for an unrelated donor will likely inspire your friends and family to consider registering to become stem cell donors. It is statistically unlikely that extended family and friends will be a match for you, as a patient, but by registering to be a stem cell donor, they could help another patient, like you, who is relying on someone they do not know to be the one match for them. So, it is important for your family and friends, who may wish to register as a stem cell donor, to understand that they are also registering for all patients in need. 

Another important way to help patients is by giving blood. Many patients in need of a stem cell transplant are also in need of blood and blood products. Anyone interested in donating blood please call us at 1 888 2 DONATE (1-888-236-6283) to book an appointment. 

More about registration and eligibility.

Why do you have to be 35 years of age or younger to donate?

The national and international transplant community has defined an ‘optimal donor’ as young – between the age of 17 and 35. Stem cells from younger donors can offer patients a possible better outcome by reducing post-transplant complications. Younger donors will remain on the stem cell network longer, thereby leading to fewer registrants needing to be recruited. Currently only 31% of the network’s composition contains potential donors 17 to 35 years.

What if I still have questions?

Should you or your immediate family have any questions or concerns about the search process for a volunteer unrelated donor, how to register as a potential donor and engage your community, or anything else related to a stem cell transplant, please call our Stem Cell and Marrow Network at 1-888-2-DONATE (1-888-236-6283) or email us at

Why are you focused on recruiting male stem cell donors?

Some large studies have suggested that using male instead of female donors can reduce graft versus host disease after a stem cell transplant. As newer and more effective ways of preventing graft versus host disease have developed in recent years, the effect of donor sex on transplant outcomes is less clear. Transplant centres, however, continue to select male donors more often. In part, this may be because more cells can be collected from male donors on average.

Canadian Blood Services is committed to making the stem cell registry as useful as possible to Canadian and international transplant centres and it is in this capacity that we continue to try and recruit as many males as possible.

We continue to monitor new data on this topic and adapt to changing trends and the preferences our transplant partners.