Bone marrow is the soft, spongy, fatty tissue inside the bones that creates red blood cells that carry oxygen and nutrients throughout the body, white blood cells which fights infection, platelets responsible for the formation of clots and anemia.
A bone marrow transplant is a procedure to replace bone marrow that has been damaged or destroyed by disease, infection, or chemotherapy with healthy stem cells which travel to the bone marrow where they produce new blood cells and promote growth of new marrow.
Bone marrow also contains hematopoietic stem cells (HSCs) which are immature blood forming stem cells. These stem cells are unspecialized and have the potential to multiply through cell division and either remains stem cells or differentiates and matures into many different kinds of blood cells. The hematopoietic stem cells are found in the bone marrow will make new blood cells throughout your lifespan.
Chemotherapy or radiation may be given before the transplant in two ways:
1. Ablative treatment –in which high dose chemotherapy, radiation, or may be both are given to kill any cancer cells. This can also kill all the healthy remained bone marrow and allows new stem cells to grow in the bone marrow.
2. Reduced intensity treatment (Mini transplant) – this treatment mostly allows older people or those with other health problems to have a transplant by giving them lower doses of chemotherapy and radiation before a transplant.
Bone marrow transplant can be categorized into three types:
1. Autologous bone marrow transplant – that involve the use of a person’s own stem cells. Stem cells are removed and harvested before patient receives a high dose of chemotherapy or radiation treatment. After the treatment is done, patient’s own cells will be placed back in the body to make normal blood cells. This also known as rescue transplant. It can only be used if the patient has healthy bone marrow.
2. Allogeneic bone marrow transplant – this transplant involve the use of cells from a donor. The donor should be closed genetic match. Special tests are done to see if the donor is a good match. Good donor match can be of parents, children, brother or sister. Allogeneic transplants do have higher risk of certain complications like GVHD. Doctors may suggest some medications to suppress immune system so that the patient’s body doesn’t attack the new cells.
3. Umbilical cord blood transplant (also type of allogeneic transplant) – in this type of transplant, Stem cells are removed from a newborn baby's umbilical cord right after birth. These stem cells are then frozen and stored until they are required for a transplant. Due to the smaller number of stem cells, blood counts take much longer to recover.
Patient needs to get several tests done to check what type of bone marrow cells he or she may need and may also undergo radiation or chemotherapy to kill off all cancer cells or marrow cells before getting the new stem cells.
Bone marrow transplants take up to a week. You need to stay in a special section of the hospital that’s reserved specially for people receiving bone marrow transplants which can help in reduces the risk of being exposed to anything that can cause infection. Bone marrow transplants procedure is similar to a blood transfusion. Donor stem cells can be collected in two ways if the patient is having allogeneic transplant:
1. Bone marrow harvest – this is a minor surgery which is done under general anesthesia. The bone marrow will be removed from the back of both the hip bones and amount of bone marrow removed is depends on the recipient’s weight.
2. Leukapheresis – during leukapheresis, donor is given five shots to help stem cells move from the bone marrow into the blood. Blood is then drawn through an intravenous (IV) line, and a machine separates and removes out the white blood cells. A needle called a central venous catheter, or a port, will be placed on the upper right portion of patient’s chest. This allows the fluid containing the new stem cells to flow directly into their heart. The stem cells then disperse throughout the body. They flow through patient’s blood and into the bone marrow. They’ll become established there and begin to grow. The port is left in place because the bone marrow transplant is performed over several sessions for a few days. Multiple sessions give the new stem cells the best chance to amalgamate themselves into the patient’s body. That process is known as engraftment. Through this port, patient also receives blood transfusions, liquids, and possibly nutrients. Doctor may suggest some medications to fight off infections and help the new bone marrow to grow. Patient will be closely monitored for any complications.
Post transplant, engraftment status of the patient will be regularly monitored. The first sign of engraftment is a rising of white blood cell count which shows that the transplant has initiated the making of new blood cells. Generally it can take few months in recovering from the bone marrow transplant depending on various factors such as:
• Donor match
• Sight of the transplant
Patient can experience some of the symptoms for the rest of their life post transplant.