Bone marrow in our bones is responsible for formation of blood cells. In fact, all the blood cells are formed by a subset of bone marrow cells known as “hematopoietic stem cells” or simple “stem cells”. These stem cells have special characteristics i.e. they can renew themselves, and have the capability to develop into any type of blood cells. Nowadays, hematopoietic stem cells can also be obtained from peripheral blood after treatment with certain growth factors or from umbilical cord. Thus, “Hematopoietic stem cell transplantation” is now also referred to as “Bone marrow transplantation”, wherein the stem cells from bone marrow that produce red blood cells, white blood cells, and platelets are injected into a recipient after a short course of chemotherapy called conditioning. Today, this is a viable option for several disorders and with continued research, success has improved markedly.
Different Types of BMT
There are two basic types of transplants, allogeneic and autologous, depending on who donates the bone marrow or stem cells.
- Allogeneic BMT: Donor and Recipient are two separate individuals and transplant is done using the stem cells of donor. It may be:
- Matched Related, where donor is HLA matched relative usually a sibling.
- Matched Unrelated, where donor is not a relative of patient and usually found from one of the various national or international registries.
- Partially Matched Related, where donor is from a patient’s family but partially matched (haploidentocal)
- Cord blood from a cord blood registry
- Autologous BMT: Donor and Recipient are same individuals, where transplant is done using patient’s own stem cells. The procedure involves giving high dose chemotherapy to patient in order to remove primary disease. Thereafter, an autologous transplant is conducted to rescue damaged bone marrow. This type of transplant has minimal complication and is preferred for diseases like multiple myeloma/lymphoma.
Who requires BMT?
There are certain conditions for which BMT is recommended.
- Malignant conditions:
- Acute Lymphoblastic leukemia (ALL)
- Acute Myeloid Leukemia (AML)
- Chronic Myeloid Leukemia (CML)
- Hodgkin Lymphoma
- Non-Hodgkin Lymphoma
- Myelodysplastic syndrome (MDS)
- Multiple Myeloma
- Germ cell tumors
- Other rare cancers of childhood
- Non Cancerous Conditions:
- sickle cell anemia
- Aplastic anemia
- Fanconi anemia and other bone marrow failure syndromes
- Inborn errors of metabolism
- Congenital Immunodeficiency syndromes
Are there any risks associated with BMT?
Yes, BMT is a complex procedure that carries significant risks and serious complications. Generally, the risks are reduced if:
- you are young – studies have shown the younger you are, the more likely the treatment is to succeed
- you receive stem cell donation from a sibling (brother or sister)
- you have no serious health conditions (apart from the condition you're being treated for)
Is BMT a surgery like kidney transplant?
No, Bone Marrow Transplant is a medical procedure. Mostly, stem cells are collected via peripheral vein and the whole procedure is like donating blood or platelet. In some patients Bone marrow harvest is done which involves general anaesthesia to the donor.
Is there any risk to the donor?
No, there is no risk to the donor. Donors are usually able to resume their duties the next day after collection of the stem cells.