Becoming a stem cell donor
In allogeneic stem cell transplants (also called allografts) the stem cells are donated by another person whose tissue type is compatible with the patient’s.
Stem cells can be harvested (or collected) from the donor’s:
- bone marrow (bone marrow harvest)
- blood stream (peripheral blood stem cell harvest)
- umbilical cord blood.
Determining donor suitability
Determining a patient or potential donor’s tissue type is done with a blood test. There is no need to take any tissue or for the donor to undergo a bone marrow biopsy.
Tissue type is not the same as blood group (A,B,O). There is no need to match the blood type of the transplant patient and the stem cell donor. Special ‘markers’ in the patient’s blood are compared with those found in a donor’s blood, to see if they are the same. These markers are also known as human leukocyte antigens (HLA), and they determine each individual’s tissue type.
Where are stem cells collected from?
Each one of us has our own unique tissue type which is determined by genetic information supplied by both of our parents. Your tissue type is like your own personal barcode. Unless you have an identical twin, your tissue type is different to the tissue type of almost everyone else in the world. As we inherit half of our genetic make-up from our mother and half from our father, there is only a one-in-four chance that a sibling will be a really good match. In reality, only about 30% of people find a full sibling match. Other donor options include:
- Stem cells can sometimes be donated from an identical twin but it is rare (syngeneic transplant).
- The donor may also be unrelated to the patient, but with a similarly matched tissue type.
- Stem cells can also be collected from donated umbilical cord blood through a cord blood banking program and used as part of a cord blood transplant.
Why is getting a good match so important?
It is essential that donor stem cells are the best possible match to the patient. This is because the donor’s immune system is transplanted along with the donor’s stem cells. A good match also reduces the risk of graft rejection, a rare complication of an allogeneic transplant where the donor stem cells fail to grow.
Matching the donor and patient helps to reduce graft-versus-host disease (GVHD), an immune system reaction commonly seen after an allogeneic transplant. In GVHD the donor’s immune system recognises the patient’s body as foreign and attacks it. Despite having a good tissue type match with the donor, transplant recipients are routinely given drugs called immunosuppressants (anti-rejection drugs), which suppress the function of the donor’s immune system for a long time after the transplant. Again, this is to help reduce GVHD and the risk of graft rejection.
What happens after I am matched with a patient?
If you match with a patient you will be contacted by the donor centre for another blood sample to confirm the match and assess if you are suitable and willing to proceed. Before donation an independent specialist will assess you medically to ensure you are medically safe to donate. In Australia, donation occurs in one of the major hospitals in your closest capital city.
If you are unable to donate your stem cells to a relative due to not being a match for them, there are other ways to help them and other people fighting cancer. Blood donation through the Red Cross Blood Bank provides essential stores required to help patients recover from chemotherapy and stem cell transplants.
How can I register to become a donor?
For more information or to register to become a bone morrow donor, contact the Australian Bone Marrow Donor Registry through the Red Cross Blood Bank in your capital city.