Bone marrow-stem cell transplantation is a process to replace the stem cells providing all the blood cells in the bone morrow with the healthy cells of another person. In this process, it is aimed to provide full recovery by replacing the improperly-functioning bone morrow stem cells as in Mediterranean anemia with the healthy ones, replacing the deficient cells as in congenital and acquired bone marrow deficiency, metabolic diseases, immune deficiency or eliminating the malignant cells in some childhood cancers especially leukemia.
In some types of cancer, it is possible to collect and store its own bone morrows of patients in complete well-being, and so the maximum anti-cancer treatment effect is achieved by providing the cells back to the patient following the high-dose chemotherapy while avoiding the drug effect of the bone marrow. Mostly applicable for adults, this method of treatment is called as ‘autologous transplantation’. All the transplant procedures with stem cells from another person are defined as ‘allogenic transplantation’, and 90% of the transplant procedures followed for children are allogenic.
The tissue types of a bone marrow-stem cell donor must be fully compatible with the patient. The best choice is a full-sibling donor with tissue compatibility. However, the probability of tissue compatibility between two siblings is 25-30%, and a sibling donor cannot be found in about 75% of the cases. In such a case, the patient’s close relatives are considered, however it is known that the probability of finding a compatible relative is very low if there is no consanguineous marriage. For these patients, the unrelated bone morrow – stem cell banks are the only choice to find a compatible donor. The tissue groups of volunteers are registered in these banks, and a compatible donor is used on demand in case of tissue compatibility.
In Turkey, there are three bone morrow banks with more than 500,000 volunteering donors within the body of İstanbul University, Ankara University and Ministry of Health (TÜRKÖK), and there are more than 30 million donors registered in many banks around the world.
Other than bone marrow, the new-blood forming stem cells are also obtained from blood circulating throughout the body (peripheral blood) or umbilical cord of a new-born child. Therefore, an umbilical cord bank is a significant resource of donor for the patients with no related compatible donor. Currently, there are more than 800,000 cord blood frozen and stored in the banks around the world. For the patients with no compatible donor, the procedure of having a haploidentical half-matched stem cell transplant from parents or siblings gives good results thanks to the recent developments, and it has became widespread.
In Turkey, bone morrow (stem cell) transplantation was first applied in 1990s, and it is widely preferred as an effective treatment method in recent years. Currently, there are 110 BMT centers, 30 of which are for children, in total. In Turkey, it is recorded that about 8000 children have been transplanted so far. Accredited by the European Society for Blood and Marrow Transplantation (EBMT), Ege University Pediatric BMT Unit is an important national center to carry out BMT procedure with both related and unrelated stem cells from the bone marrow or umbilical cord banks in our country and around the world. In this unit, approximately 50 children have bone morrow transplantation each year. Thanks to this unit, numerous children diagnosed with malignant congenital diseases or cancer get completely healthy again. Bone morrow stem cell transplantation is a serious treatment method that may result in life-threatening conditions, and therefore, it is crucial to have it in a fully-equipped hospital with a qualified personnel.