Stem cell FAQs

Whether you're a donor or a patient, understanding the stem cell donation and transplant process is an important part of your journey. Find the answers you need below in our list of Frequently Asked Questions and common myths.

If you or your immediate family have more specific questions or concerns not covered by this page, please call 1 888 2 DONATE (1-888-236-6283) or email us at

Join our stem cell registry

Frequently asked questions

What are stem cells?

Blood stem cells are immature cells that can develop into the cells present in the bloodstream, including:

  • Red blood cells, which carry oxygen throughout the body.
  • White blood cells, which fight infections.
  • Platelets, which help control bleeding.

Blood stem cells are not embryonic stem cells. They come from bone marrow, circulating (peripheral) blood or umbilical cord blood. When patients need a stem cell transplant, it means that their bone marrow (stem cell factory) has failed due to an illness.

Patients who undergo chemotherapy or radiation treatment may also need a transplant of healthy stem cells to help heal and re-boost their immune system.

How stem cell donation works

What is bone marrow?

Bone marrow is the soft tissue inside our bones that acts as a factory, producing blood-forming stem cells. When diseases affect the bone marrow, and they cannot produce healthy stem cells, a stem cell transplant may be a patient’s best treatment option.

What is Canadian Blood Services Stem Cell Registry?

Canadian Blood Services Stem Cell Registry—formerly known as the OneMatch Stem Cell and Marrow Network—is dedicated to recruiting and finding healthy, committed volunteer donors for patients in need of blood stem cell transplants. We belong to an international network of registries comprising over 80 participating countries, with over 40 million donors from around the world. Yet, a match for a patient in Canada can only be found about 50 per cent of the time.

Canadian Blood Services Stem Cell Registry operates according to international standards established by the World Marrow Donor Association (WMDA), the international organization that promotes the ethical, technical, medical and financial aspects of stem cell transplantation. We coordinate searches in Canada and with other international registries to work towards a single goal: helping patients get the stem cells they need.

How does a stem cell transplant work?

A stem cell transplant replaces a patient's unhealthy blood stem cells with the matching donor's healthy stem cells. There are three sources of stem cells used in transplant:

  1. Bone marrow
  2. Peripheral (circulating) blood
  3. Umbilical cord blood

The type of stem cell donation is determined by the transplant physician and transplant team based on the needs of the patient. Several factors are taken into consideration by the transplant team to best determine the type of stem cell donation for the patient. These factors include:

  • Whether a matching donor is available within the patient's family or a volunteer unrelated donor is available somewhere in the world.
  • The patient's prognosis, also known as their status and likely course of their disease.
  • The height and weight of the patient and the donor.
  • The age of the donor and the patient.
  • The urgency of the transplant.

How stem cell donation works

How are donors matched to patients, and how does ethnicity play a role?

Stem cell matches are determined according to DNA markers called Human Leukocyte Antigens (HLA) which are known to be important when matching a patient to a donor. These antigens are found on the surface of white blood cells and are inherited from our parents.

The best potential HLA match is from a sibling. However, most patients have about a 25% chance of a sibling match. The rest may rely on a volunteer unrelated donor from outside their family.

A patient's best chance of finding a matching donor outside their family is among those who share their ethnic background. Therefore, we need donors from as many diverse ethnic and mixed-race backgrounds as possible.

When you register to join Canadian Blood Services Stem Cell Registry, a sample of your DNA is obtained to identify your HLA which is entered into our database. This database allows us to search for potential donors who match a patient requiring a stem cell transplant. The closer the match between patient and donor, the better the outcome for the patient following the transplant.

Some patients have many potential donors because they have inherited HLA that's more commonly found in the registry. These HLA occur with varying frequency in different ethnic groups. For example, those HLA common in Caucasians may rarely be found in the Asian community, and vice versa.

While not always the case, patients are more likely to find a matching donor among those who share their ethnic ancestry, which makes an ethnically diverse donor registry extremely important.

More on stem cell donor eligibility

Does it cost me anything to register or donate?

No. Registration is free, and you won't be charged for any part of the testing or donation process should you be a match. For example, if you must go to another city or province for the stem cell donation procedure, your travel, food, accommodation and other costs are covered for you. In some special circumstances, some or all costs for a companion may also be covered.

While the procedure and recovery will take you away from work for only a short time, most employers are willing to give sick leave or paid leave to stem cell donors. If this is not the case, a certain amount of lost wages may also be covered by Canadian Blood Services.

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

Working with Canadian Blood Services Stem Cell Registry, your transplant team is responsible for locating an unrelated donor if you have not been matched with a family member. It is not the responsibility of you or your family to find your donor. If you would like to know whether you have a match within your own family members, please speak with your doctor and their team.

Anyone who joins the Canadian Blood Services Stem Cell Registry is making a commitment to be available for any patient in need. Once part of the blood stem cell registry, your Human Leukocyte Antigens (HLA) will be included in searches for all patients, both in Canada and around the world.

How is a volunteer unrelated donor found?

There are many steps in finding a donor. This is the responsibility of your transplant team, in partnership with Canadian Blood Services Stem Cell Registry.

The first four steps of the process to finding the most suitable match are:

  1. The patient’s transplant team submits a search request to Canadian Blood Services Stem Cell Registry.
  2. The stem cell registry sends a report to the transplant team listing the potential unrelated donors.
  3. The transplant team identifies the donors to contact and submits their request to the stem cell registry which then tries to contact the donor(s) directly. For international donors, the request will be forwarded to the applicable international registry which will contact their donor(s) directly.
  4. Once a donor is contacted, the applicable registry confirms both their interest in proceeding to complete a health screening questionnaire and their eligibility before arranging for additional blood testing.

How stem cell donation works

How do registered donors donate their stem cells?

After you've been accepted as a blood stem cell donor, the donation team will choose which procedure is right for the patient. There are two possible donation procedures:

  1. Peripheral blood stem cell (PBSC) donation

    PBSCs are collected from circulating (peripheral) blood. Since only a small number of blood stem cells can be found in our actual bloodstream at any moment, PBSC donors receive a small injection under the skin of a drug called granulocyte colony stimulating factor (G-CSF) every day for four days prior to the donation. These injections stimulate the production and release of stem cells from the bone marrow into the bloodstream.

    The stem cells are then collected using a procedure called apheresis, where only the stem cells are separated and collected from the bloodstream during donation. The remaining blood components are safely returned to the donor. This is a non-surgical procedure and takes approximately four to six hours. Admission to the hospital is not required for PBSC donation. In some cases, a second donation is required the following day. Approximately 80% of collections are completed using this procedure.

  2. Bone marrow

    Bone marrow stem cell donation is a surgical procedure performed under anesthesia. The physician administering the donation uses a special hollow needle to withdraw liquid marrow from the back of the pelvic bones.

    The procedure usually lasts 45 to 90 minutes. The amount of bone marrow collected can range from 0.5 litres to 1.5 litres depending on the number of stem cells the patient needs. This is calculated based on the height and weight of the donor and patient. Approximately 20% of collections are completed using this procedure.

How stem cell donation works

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

Once the donation is completed, a specially trained courier hand-delivers the donated stem cells from the collection centre/hospital to your transplant centre/hospital. Stem cell units from umbilical cord/placental blood travel by medical courier who keeps the product frozen until ready for thawing and infusion.

Canadian Blood Services Stem Cell Registry ensures travel documents and plans are in place to safely travel within Canada and around the world.

What is the outlook for patients who receive stem cell transplants?

While there are no guarantees for the patient, a transplant may be the best hope of returning to good health. Transplant outcome depends on many factors, including:

  • How well the donor and patient are matched
  • The type and stage of the disease
  • The health and age of the patient
  • The age of the donor and how many stem cells are transplanted

Do donors always follow through when they get the call to donate?

The majority of people who register to donate stem cells have a strong commitment to helping any patient in need. However, after months or years of being on the registry, when we reach out to potential donors who are a special match for a patient, some are either unreachable or are no longer available to donate.

A potential donor’s availability can change for many reasons, including changes to their health that may affect their donation eligibility. As a result, there are instances when some people may decline to donate. Whenever possible, it’s important for us to identify this before someone becomes a potential match.

That’s why we are now reaching out more regularly to potential donors to provide information about the program and to ask all potential donors to recommit to the stem cell registry every year or so by clicking a button. If a search for a patient identifies someone as a potential match, we want to be able to give both the donor and the patient positive news.

If you’re currently registered with Canadian Blood Services Stem Cell Registry, but haven’t heard from us yet, contact us directly to update your commitment by calling 1 888 2 DONATE (1-888-236-6283).

Why we need donor commitment

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 publicly banked 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 the patient has unusual or uncommon HLA markers. In this case, the transplant team may consider other options for the patient.

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

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

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

To find out if you would be able to make contact with your donor, talk to your transplant team.

How can my family and friends help?

The search for an unrelated donor will likely inspire your family and friends, if they're eligible, to consider registering to become blood stem cell donors themselves. By registering to become a stem cell donor, they could help another patient who is relying on someone they don't know to be the match for them.

It's important for family and friends who may wish to register as a stem cell donor to understand that they're also registering for all patients in need, worldwide.

If you would like to organize a campaign or need materials to support recruitment, please email us at

Another important way to help patients is by donating blood. Many patients in need of a stem cell transplant are also in need of blood and blood products as part of their treatment on a weekly and sometimes daily basis. Anyone interested in donating blood can book their appointment online.

More on stem cell donor eligibility

Why do I have to be 17-35 years of age to register, and up to what age can I donate?

Transplant physicians around the world tend to select younger donors to achieve better transplant outcomes for patients. Research suggests that the age of a blood stem cell donor is one of the most important characteristics influencing patient survival following a blood stem cell transplant. In particular, younger donors are associated with better survival rates for patients.

Stem cells from young donors can offer patients better possible outcomes by reducing transplant complications such as graft-versus-host-disease (GVHD). 

In compliance with international accreditation standards, younger donors will also remain on the stem cell registry longer, until their 60th birthday. By allowing registrants to donate up to the age of 60, the chances of a registrant being selected for a longer time are increased.

In addition, government resources allocated to running the program and optimizing the utility of the overall registry are maximized, balancing fiscal responsibility with clinical benefit to patients.

More on stem cell donor eligibility

Why are you focused on recruiting male stem cell donors?

Large-scale studies have suggested that using male donors can reduce graft-versus-host-disease (GVHD), which is an immune response that occurs in a patient after transplant, when the donor stem cells mistakenly attack the patient’s own cells and tissues.

Even as newer and more effective ways of preventing GVHD continue to develop, the effect of donor gender on transplant outcomes is still unclear.

Transplant centres continue to prefer to select male donors because, on average, more stem cells can be collected from male donors. Physicians select males three out of four times because they tend to be physically larger, and therefore yield more blood stem cells at the time of collection. More blood stem cells transfused into a patient typically decreases the number of days for those cells to begin working (engraftment) and increases the chance of a successful outcome for the patient. 

We are committed to making the Canadian Blood Services Stem Cell Registry as effective as possible for both Canadian and international transplant centres, which is why we continue to try and recruit as many males as possible. We also continue to monitor new data on this topic and adapt to the clinical practices of our transplant partners.

More on stem cell donor eligibility

What if I still have questions?

If 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 an unrelated blood stem cell transplant, please call 1 888 2 DONATE (1-888-236-6283) or email us at

Myths about stem cell donation

Learn the facts behind some common misconceptions about donating stem cells.

Stem cells are taken from the spinal cord.

False. Blood stem cells are not taken from the donor's spinal cord. For a bone marrow donation, stem cells are taken from the iliac crest which sits at the back of the pelvic bone. For a peripheral blood stem cell donation, stem cells are taken from a blood draw with a needle in the arm, much like a plasma or platelet donation, using a non-surgical procedure called apheresis.

All stem cell donations involve surgery.

False. Some donations involve surgery and others do not. Registered stem cell donors may be asked to donate stem cells from their peripheral blood or bone marrow. Bone marrow donation is a day surgical procedure done in an operating room. Peripheral blood stem cell donation is a non-surgical procedure done in an outpatient clinic. How stem cell donation works

Expectant mothers may also consent to donate their umbilical cord blood, rich in life-saving stem cells, after the safe delivery of their baby. More on cord blood donation

Stem cell donation is painful.

False. For bone marrow donation, the collection of stem cells is taken from the iliac crest and is done using general anesthetic, so the donor does not experience pain during the donation procedure. Donors have described having a mild-moderate soreness, bruising and aching at the lower back that can last for a few days to several weeks after their donation.

For peripheral blood stem cell donation, only the stem cells are separated and collected during donation through a non-surgical procedure called apheresis. This is done in an outpatient clinic and takes approximately four to six hours. Donors have described feeling some mild discomfort during the procedure including feeling light-headed, nauseous and/or cold. How stem cell donation works

For expectant mothers who have consented to donate cord blood, the stem cells are collected after the safe delivery of the baby and placenta/umbilical cord. We do not interfere with the normal process of labour or delivery. More on cord blood donation

Stem cell donation involves a lengthy recovery process.

False. The recovery period for bone marrow donation varies from donor to donor. Most donors experience fatigue, soreness at the donation site, bruising and lower back pain for a few days to several weeks. Donors may also experience discomfort when walking, standing or sitting. Some donors have reported difficulty climbing stairs for a week or two after their donation. Donors are advised to avoid strenuous activities for 2 to 3 weeks after donation.

The recovery period for peripheral blood stem cell donation is often much quicker. Most donors say they were able to return to work the day after their donation. Some donors have reported experiencing headaches, bone or muscle pain, nausea, insomnia and fatigue lasting between several days to a week following their donation.

If I donate stem cells, they cannot be replaced.

False. The body replaces donated blood stem cells within six weeks. After donating, most donors are back to their usual routine in a few days.

I come from a large family, so if I ever need a stem cell transplant, I should have no problem finding a match within my family.

False. The requirements for finding a genetic match are so precise that fewer than 25% of those in need find a match within their own family. Patients have better odds of matching with someone who is unrelated and shares their ethnic background. That's why we need culturally diverse individuals between the ages of 17-35 to register to join Canadian Blood Services Stem Cell Registry, and expectant parents to consider donating their baby's cord blood to Canadian Blood Services' Cord Blood Bank.