What is Bone Marrow Transplantation?
Bone marrow transplantation is a treatment method which is practiced when bone marrow dysfunction develops in patients with severe blood disease, certain cancers and diseases of immune system or genetic disorders.
Why is bone marrow transplantation important?
Bone marrow can be accepted as a factory where red blood cells, white blood cells and platelets are produced from stem cells. Since any damage to this factor can directly deteriorate stem cells, production of blood cells is also affected. Therefore, stem cells should be replaced for the treatment of some diseases. The procedure is colloquially called bone marrow transfer, but it is actually the transplantation of stem cells harvested from certain sources such as bone marrow, peripheral blood and cord blood. Blood cells are red blood cells, white blood cells and platelets. Red blood cells carry the oxygen which has vital importance for the body, while white blood cells help fighting against infections and platelets control the bleeding. These three series should function properly to be a healthy person. When the disease involves the bone marrow and causes dysfunction, transplanting stem cells that are harvested from bone marrow, peripheral blood and cord blood can be the best treatment choice.
Which diseases require bone marrow transplantation? Leukaemia and Lymphomas, Multiple myeloma and some other plasma cell diseases. Myelodysplastic syndromes and myeloproliferative diseases. Severe aplastic anemia and other bone marrow failures: Severe combined immune deficiency and other genetic immune system disorders. Hemoglobinopathies. Some genetic metabolic disorders. Other cancer cases to administer high-dose medication/ radiotherapy.
Who are donors of bone marrow (stem cell) and how are stem cells stored?
Donor is the person who donates stem cells. Being a donor requires tissue antigens (HLA) be compatible with the patient. Tissue antigen compatibility is common in siblings and therefore, siblings are analyzed first. If there is no match sibling, mother, father and other family members are screened. If a match donor cannot be found among the relatives, bone marrow banks are screened. First, local banks are screened and if no match donor is found, screening continues in international banks.
Is the health of bone marrow (stem cell) donor affected negatively?
No, donation of stem cell does not harm the donor's health. If a person will be stem cell donor for a relative, age limit is not considered. However, people who want to donate stem cell in a tissue bank should be 18 to 55 years old. The donor is administered a certain drug for 5 days in order to mobilize stem cells into bloodstream. When count of stem cells in blood reaches a certain level, they are harvested from a vein in the arm such as blood sampling.
What are types of bone marrow transplantation?
From the patient's own body (autologous)
From someone else to the patient (allogeneic)
Allogeneic bone marrow transplant requires a match related or unrelated donor.
How is transplantation performed?
Autologus stem cell transplant is not an option for all diseases. However, high-dose chemotherapy and/or radiotherapy is/are necessary according to the disease. High-dose chemotherapy causes death of healthy stem cells. Thus, patient’s stem cells are harvested, frozen and stored before they are damaged. The frozen stem cells are thawed to body temperature and infused to the patient, after high-dose medication treatment and/or radiotherapy is/are completed. In allogeneic transplantation, stem cells are not harvested from patient's own body but from a healthy match donor. The cells harvested from the donor are transplanted again after the patient receives high-dose medication treatment and/or radiation therapy.
What should patients expect in post-transplantation period?
For all transplants, the most critical problem is recurrence of the disease. Otherwise, patients do not experience many problems following autologous transplantations. The major problem may develop after allogeneic transplantations. Although stem cells are transplanted from match donor or even from a sibling, the donor and the patient are foreign for each other. Strong cells of the donor react against recipient's cells and damages them; thus, clinical picture of a disease, called GVHD (graft versus host disease), may develop. This picture is accompanied by skin rashes, mouth sore, dry eye, diarrhea and jaundice. Patient will be given various medications to hamper these side effects during transplantation, but they can be observed despite all these efforts. Our aim is to suppress GVHD to a mild clinical picture. Healthy cells of the donor also damage the diseased cells and this is an expected effect of the treatment.