What happens during bone marrow transplant?
Bone marrow is a soft tissue present inside the bones that produce WBCs, RBCs and platelets. If the stem cells fail to produce normal and healthy blood cells, then doctors recommend bone marrow transplant for replacing diseased bone marrow with a healthy one. This new stem cell is taken from a donor and implanted in the recipient’s body that further helps to produce healthy blood cells.
Sometimes for the treatment of certain cancers, the bone marrow is taken from the body of the patient itself before transplanting it back into their bodies. In the middle of the two procedures, the patient is made to undergo radiation treatment and chemotherapy, which end up destroying the healthy bone marrow. The bone marrows retrieved from the body of the patient before radiation and chemo is then transplanted.
The bone marrow transplant procedure is carried out in a medical facility and involves following steps:
- Collection of donor stem cells:
The bone marrow cells are harvested from a donor if it is an allogenic bone marrow transplant, while for autologous bone marrow transplant patients own cells are retrieved before starting with chemotherapy.
The donor cells can be collected in two ways:
Peripheral blood stem cell donation (Leukapheresis)
For Peripheral blood stem cell donation (PBSC), the donor is given shots of substance that will help the movement of stem cells from the bone marrow to the bloodstream. This goes on for several days. During leukapheresis, the blood is drawn through a needle in the patient’s arm and collected through an intravenous (IV) line. A machine will separate out the part of white blood cells that contain stem cells from other components of the blood. These stem cells might be stored and frozen, especially in case of autologous transplant.
Bone marrow donation: It involves a minor surgery performed under general anesthesia, which means the donor will be unconscious and feel no pain during the procedure. Then the surgeon will collect the bone marrow from the back of both hip bones using a needle. The amount of marrow that can be removed is determined on the basis of the weight of the bone marrow recipient.
In most cases, PBSC donation is used as it is a simple process that does not involve surgical risks. Also, it does not cause any discomfort to the patient as opposed to bone marrow donation, where the donor may feel a little sore around the hip for a few days.
Cord blood: In cases where the cord blood is used, the stem cells are obtained from the placenta and umbilical cord donated by the mother of a newborn baby. The mother will decide if she wants to donate the cord long before the baby is born. It doesn’t affect the baby health in any way. The cells are then frozen and stored until needed for transplant.
- Conditioning process
Once the pre-transplant tests and procedures are done, the recipient will go through a process called ‘conditioning’ to prepare their body for transplant. During a conditioning regime, they will have chemotherapy and/or radiation therapy. This is required to:
- Destroy the cancer or diseased cells in the body as a treatment modality for the underlying condition.
- Suppressing the immune system (to allow it to accept the transplant cells)
- Prepare the bone marrow for the new stem cells
The type and amount of conditioning the patient receives depends on several factors, including the disease being treated, recipient’s overall health and the type of bone marrow transplant. A person may undergo chemotherapy or radiation, or have a combination of both these treatments during their conditioning.
Some possible side effects of the conditioning procedure include common adverse effects related to chemotherapy and radiation, such as:
- Nausea and vomiting
- Mouth sores or ulcers
- Diarrhea
- Hair loss
- Risk of infection
- Infertility issues
- Anaemia
- Weakness or fatigue
- Complications related to other organ, such as heart, liver or lung failure
The doctor may prescribe some medications or recommend other measures to reduce the side effects.
Reduced-intensity conditioning
The top bone marrow transplant hospitals in India offer this kind of conditioning for some patients. This type of conditioning process involves the use of lower doses or different types of chemotherapy and/or radiation during the treatment. The doctor will recommend reduced-intensity conditioning on the basis of the patient’s age and overall health status.
This conditioning will destroy some diseased cells and suppresses the immune system. The donor’s cells are then infused into recipient’s body, and over time they will replace the cell in the bone marrow. The immune factors in the donor cells help fight the cancer cells and treat the condition.
- Bone marrow transplantation
For the transplant, a central line is used to transfer the collected stem cells into the recipient’s body. This is done after the conditioning process is complete.
A central venous catheter, or port, is installed on the upper portion of the patient’s chest. The fluid containing new stem cells flows directly into the heart through the catheter and gets dispersed throughout the body. As they reach to the bone marrow, they will become established there and grow to increase their number. The blood cell count will return to normal within a few weeks. The patient will have regular blood count tests, meanwhile, to monitor the progress.
The transplant infusion itself is a painless process and the recipient remains awake during the procedure. It takes a few hours to complete the procedure.
Stem cells that were frozen have to be thawed before the transplant. They contain a preservative that may cause certain side effects in the patient. The doctor will administer certain medicines in such cases to help prevent any complication. Sometimes, extra fluids are also given to flush the preservatives out of the body.
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