WHAT IS BONE MARROW TRANSPLANTATION?
Baskent University Ankara Hospital Bone Marrow (Hematopoetic Stem Cell) Transplantation center was built in 2013. Our team consists a hematology professor, an associate professor, a hematology specialist and a clinical nurse coordinator. Certified biologist, technicians and nurses work at therapeutic apheresis center and stem cell processing and cryopreservation unit. Rooms have positive pressure HEPA filter system which can turn into negative pressure when needed. The transplant unit is seperated from other units and all patient, doctor, secretary, nurse rooms are arranged to minimize infections that can be transferred from outside. All patient rooms are equipped with TV, internet.
Stem cell transplantation is a therapeutic option for some benign and malignant diseases. Stem cells needed for transplantation can be collected from peripheral blood, bone marrow or cord blood. Stem cells have the ability to reproduce all the cells of bone marrow and blood.
What are the diseases that can be treated with stem cell transpantation?
- Multiple myeloma
-Acute myeloid leukemia and acute lymphoblastic leukemia
-Chronic myeloid leukemia
-Hodgkin lymphoma and non-Hodgkin’s lymphomas
-Bone marrow deficiency syndormes
-Paroxysmal nocturnal hemoglobinuria
-Some hereditery disorders (thalassemias, immune deficiencies)
There are mainly two types of stem cell transplantation: autologous stem cell transplantation and allogeneic stem cell transplantation. In autologous transplantation patient’s stem cells are collected from the blood and given back after treatment. In allogeneic transplantation, stem cells are collected from another person (who can be a family member or unrelated person). Type of treatment is decided according to the disease and disease status.
How are stem cells collected and frozen?
Usually stem cells circulating in bloodstream are collected. A few days (4-5 days) before collection a drug called G-CSF is given to the donor subcutaneously which increases the number of stem cells made. Then the stem cells are collected using an apheresis machine. This procedure may last 2-4 hours. This process does not require general anesthesia and it is not an operation. Rarely numbness of lips or cramps in extremities may ocur. There is no major risk fort the donor. This is like blood donation.
Stem cells collected are counted and then given to the patient soon or somteimes they are frozen. When stem cells are freezed at -196°C they maintain their viability for years. They are thawed and given like blood transfusion when the patient needs. These stem cells find their ways in bone marrow and start proliferating and producing new blood and marrow cells in 2-4 weeks. The immune system recovers in 2-3 months in autologous and 1-2 years in allogeneic transplants.
How is autologous transplantation done?
The patient receives chemotherapy first to kill or decrease cancer cells. Then patient’s stem cells are collected and frozen. After that high dose chemoterapy is given to remove remaining cancer cells or to prevent relapses. These chemotherapies also remove blood producing cells left in bone marrow. After that collected stem cells are given back and new cells are produced in bone marrow. Since these are patients own stem cells less complications occur in autologous transplantations.
How is allogeneic stem cell transplantation done?
In this case stem cells are provided from healthy donors who are preferrably HLA full matched or partially matched brother or sisters or if not found other relatives or unrelated donors. Full matched donors are always preferred but it is not always possible to find such donors. So partially matched donors can be used sometimes. There are national and international donor registries.
In allogeneic transplantation patients receive high dose chemotherapy to kill cancer cells which also gets rid of bone marrow cells. Immune system also stops working. Healthy donor’s stem cells are given after this chemotherapy to replace and produce new blood cells. A number of complications might ocur after allogeneic transplant. Graft versus host disease is one of the most important complications which is due to white blood cells produced from donor’s stem cells recognizing host’s tissues as foreign and attacking them. This can be acute which occurs in a few weeks after the transplant or chronic which ocuurs later and lasts longer. Immunesuppressive drugs are given to prevent and treat. Complications of high dose chemotherapy like infections, mucositis, bleeding, diarrhea or anemia may ocur. Rarely graft failure happens which is loss of donor stem cells. If the patient had advanced stage disease, there is chance the disease might come back after the transplant.