Bone marrow is the soft, fatty substance inside the bones where immature stem cells produce blood cells. However, the marrow sometimes gets damaged or diseased and stops producing healthy ones. To counteract this, a bone marrow stem cell transplant is performed, which replaces the existing marrow and cells with healthy ones.
Thankfully, only a small variety of diseases cause damage that requires a transplant as treatment. These include:
- Leukemia, which targets the marrow and interrupts blood cell production
- Multiple myeloma, which affects plasma cells in bone marrow
- Plasma cell disorders
- Other bone marrow diseases that affect the blood cells produced in the marrow, such as sickle cell anemia (a disfiguration of red blood cells) or congenital neutropenia (too few white blood cells)
- Severe immunodeficiency syndromes
Types of Bone Marrow Transplants
Transplants can be autologous, allogeneic, or umbilical cord blood transplants.
Autologous bone marrow (or “rescue”) transplants are performed with the person’s own stem cells. Before receiving chemotherapy or similar treatments, healthy stem cells are removed and cryopreserved (frozen quickly at extreme temperatures). After chemotherapy, they are replaced, so that blood cells are generated normally.
Allogeneic bone marrow transplants occur when one person’s stem cells are put into another person’s body. A donor with properly matching genes is found through blood tests. Normally a close relative is the best option, but not always. National registries are available for those whose relatives do not match or are unable to donate.
Umbilical cord blood transplants take cells from the umbilical cord and store them (much like an autologous transplant) until they are needed. Since the cells are so immature, matching is less important, but regeneration also takes longer.
Receiving a Bone Marrow Transplant
Before the transplant, the patient must fully understand the risks, benefits, and chances of success of a bone marrow transplant. A complete exam is performed by doctors and specialists to ensure the best odds. A few days before the procedure, the patient will be evaluated again, provided with additional hydration, along with all the other necessities.
Getting a blood marrow transplant is much like getting a blood transfusion and generally requires no surgery. A central venous catheter is placed in a large vein, usually in the neck, chest, or groin. The stem cells are sent into the blood and travel through the bloodstream to the marrow.
Donating Bone Marrow
Giving bone marrow can be a little more arduous. The donor must undergo similar testing and exams to ensure they are completely healthy before the marrow is extracted. There are two options for donating: bone marrow harvest or leukapheresis.
Bone marrow harvesting is considered a minor surgery. The donor is given an anesthetic, so that they do not feel any pain and sleep through the operation. A large needle is placed into the back of the hip bones into the marrow, which is then withdrawn.
Leukapheresis, on the other hand, requires a series of shots for a few days beforehand, which moves stem cells out of the bone marrow and into the blood. These peripheral blood stem cells are then collected by drawing blood with a needle from a vein in one arm and sent into a cell separation machine, which takes out the stem cells and then sends the the rest of the blood and plasma back into the donor through a needle in the other arm.
