Finding a cure

The basics of transplantation

During a blood stem cell transplant, the patient receives healthy blood stem cells from a donor. The donor’s blood stem cells travel through the bloodstream to the patient’s bone marrow where they begin to produce new blood cells (red blood cells, white blood cells and platelets).

Blood stem cell transplantation is a complex procedure that requires a team of healthcare professionals, including a transplant physician, transplant nurse, and other specialists. The patient needs to be carefully monitored before, during, and after the procedure for any complications. However, for many patients with blood cancers and other diseases, a blood stem cell transplant can be a life-saving treatment option.

The patient journey

Type of transplant

There are two types of blood stem cell transplants: autologous and allogeneic.

Autologous transplants use the patient’s own stem cells, which are collected before the patient receives high-dose chemotherapy or radiation therapy. After the treatment, the patient’s stem cells are infused back into their body to help restore the blood-forming cells that were destroyed by the treatment.
Allogeneic transplants use stem cells from a donor who is a close genetic match to the patient. The donor’s stem cells are collected either from the bone marrow or peripheral blood or cord blood and then infused into the patient’s bloodstream. An allogeneic donor can be either be a relative of the patient or a completely stranger.

Start with a family search

To find a matching donor, the patient’s tissue type is determined using a simple blood test. This test checks the patient’s human leukocyte antigens (HLA), which are proteins found on the surface of cells that help the immune system recognize self from non-self. Once the HLA type is determined, the search for a matching donor begins.

The first step in the search for a matching donor is to look for a donor within the patient’s family. Siblings have a 25% chance of being a full HLA match, while parents and children have a 50% chance of being a half HLA match. If a suitable family donor cannot be found, the search is extended to the global database: Search & Match Service.

Expanding to a global search

The global donor database of volunteer donors, which is managed by the World Marrow Donor Association (WMDA), is made up of over 40 million volunteer donors from around the world. The registry includes both unrelated adult volunteers and units of cord blood from public cord blood banks. The WMDA coordinates the search process and identifies potential matching donors and/or cord blood units for the patient.

The WMDA Search & Match Service uses sophisticated computer algorithms to match the patient’s HLA type with that of potential donors and/or cord blood units. The search is not limited to donors from the patient’s own country or ethnicity, as matches can be found from anywhere in the world.

If a matching donor is found

If a matching donor is found, the donor will be contacted to confirm their willingness to donate by its local registry. The donor will then undergo a thorough medical evaluation to ensure that they are healthy and able to donate. If the donor is cleared for donation, the stem cells are collected and transplanted into the patient.

In some cases, a suitable match cannot be found in the registry. In these situations, the patient’s medical team will explore other treatment options or consider a transplant from a partially matched family member or an unrelated donor with a less than perfect match.

Transplantation & Recovery

After the donor has been confirmed, you will need treatment before the transplantation can be carried out. Usually, patients receive high doses of chemotherapy and possibly radiation. These treatments destroy the defective blood stem cells in the bone marrow and create space for the new, healthy stem cells. It also suppresses your immune system so that it will not attack the new stem cells after transplantation.

After the transplantation, you will stay in hospital until your immune system recovers and physicians are sure that the procedure was successful. During your time in hospital, specialist doctors and nurses will carefully watch for signs of chemotherapy and radiation side effects, infections, Graft vs. Host Disease or graft failure.

Risks of transplantation

A bone marrow, peripheral blood stem cell or umbilical cord blood transplantation is a medical procedure, and no procedure is risk-free. Patients should always consult their transplant physician about the associated risks. Outcomes have improved considerably thanks to collaboration between scientists, clinicians and nurses within scientific communities that collect data on procedures and analyse outcomes. Disease-free survival rates depend on various aspects, including disease stage and degree of HLA matching between donor and patient.

Infection: the risk of infection is increased after transplantation because the patient’s immune system is weak. Infections can be serious and may be caused by bacteria, viruses, fungi or yeast. The risk of infections decreases as the immune system recovers.

Graft vs. Host Disease: GvHD is a common complication for people who receive blood stem cells from a donor. It can vary from mild to life-threatening. In GvHD, the new blood stem cells attack the recipient’s body. Acute GvHD occurs within 90 to 100 days after transplantation; chronic GvHD occurs more than 90 to 100 days after.

Graft failure: this means that the new blood stem cells do not function properly. It can happen if the patient’s immune system rejects the new blood stem cells, if the number or quality of the transplanted cells was insufficient, or if the transplanted cells are damaged by infection or toxic substances after transplantation.

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