World Bone Marrow Donor Day: more than 28 million people in the world are already bone marrow donors

Every third Saturday in September, World Bone Marrow and Cord Blood Donor Day is celebrated. This is an initiative promoted by the World Marrow Donor Association (WMDA), with the aim of reminding the world population of the importance of donating marrow, as well as of informing themselves adequately before making such a decision, which can save many lives.

Currently, more than 28 million people around the world are already bone marrow donors, to which must be added the more than 650,000 cords of Umbilical Cord Blood (UCB). In Spain there are already more than 230,000 bone marrow donors and some 60,000 cords stored in public banks.

On the occasion of this important and important date we have the collaboration of Dr. Anna Sureda, head of the Clinical Hematology Service at the Institut Català d’Oncologia-Hospitalet and head of the Hematology Service at the Hospital Universitari Quiron-Dexeus in Barcelona, to answer the main questions that arise around bone marrow donation.

Dr. Sureda, what does donating bone marrow involve?

Bone marrow transplantation is the only therapeutic option for many patients with onco-haematological diseases. In order for an allogeneic transplant to be performed, a compatible donor is essential, so the patient’s siblings are the most likely to be compatible. However, only 1 in 4 patients has a compatible sibling. Hence the creation, many years ago, of registries of unrelated donors, who are altruistic donors. The system used and analyzed to assess patient-donor compatibility is the HLA system, a very diverse complex of antigens that requires many donors in order to find a compatible donor.

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It is important to emphasize that bone marrow donation is voluntary and altruistic, as is becoming a donor in a registry of unrelated donors. When a person becomes a donor, he/she will be called for an eventual donation, if there is a patient with a hematological disease in whom an allogeneic transplant can be applied and he/she is compatible. When contacted, the donor decides whether to agree to the donation.

What does the procedure consist of?

Bone marrow is collected through multiple punctures performed in the anterior iliac crests and posterior iliac crests. The total volume of bone marrow collected depends on the weight of the patient to be transplanted, i.e. the volume is lower in pediatric patients, for example, than in adults.

Bone marrow extraction is performed under general or epidural anesthesia and sometimes involves a hospital stay of 1-2 days. Currently, however, there are many transplants that are not performed using bone marrow progenitors but peripheral blood progenitors.

In allogeneic bone marrow transplantation, the patient’s diseased hematopoietic progenitors are replaced by healthy ones from the chosen donor. It is not surgery. The bone marrow progenitors are infused into the patient through a central venous catheter, like a blood or platelet transfusion. In order for the patient not to reject these new progenitors, and to eliminate remnants of the disease that the patient may have before the transfusion, chemotherapy and/or radiotherapy are administered at high doses, which is called conditioning treatment.

Are there any side effects?

Transplantation may be associated with side effects. On the one hand there are those related to chemotherapy and radiotherapy and, on the other hand, to the fact that the donor is compatible with the patient but not identical. In this case the donor lymphocytes that are infused with the hematopoietic progenitors recognize some of the recipient’s cells as foreign and can attack them. This is an “immune attack”, which is called graft-versus-host disease.

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Can everyone be a donor?

Not everyone can be a donor. Since 2018, the age of an altruistic unrelated donor has been set between 18 and 40 years, this being the maximum age in cases of unrelated donors, set by the Spanish Registry of Bone Marrow Donors (REDMO). The donor must not have a history of cardiac, hepatic, autoimmune, infectious-contagious or neoplastic pathologies.

In cases of family donors there is no age limit. It is a factor that is related to potential health problems, something that increases with age. That is why, in case there are two HLA identical siblings with the patient, the younger one will be chosen, as far as possible.

How many people may need bone marrow donation and for which pathologies is it indicated?

Bone marrow transplantation is indicated for specific hematological pathologies. The most common indications are acute leukemias (both myeloid and lymphoblastic), myelodysplastic syndromes (malignant bone marrow diseases in which the bone marrow is unable to produce enough red blood cells, white blood cells and platelets) and in chronic myeloproliferative syndromes (hematopoietic stem cell diseases in which more white blood cells, red blood cells and platelets are produced than normal and can develop into leukemia).