BMT is a procedure, where healthy stem cells are transplanted into patient’s body, after appropriate treatment. Healthy stem cells can be collected from the patient, when he becomes disease-free after treatment. They can also be collected from fully / half HLA matched family donor, unrelated donor and cord blood. Stored stem cells of the patient / donor / cord blood are transfused into patient’s blood stream, quite similar to blood transfusion.
Allogeneic Transplants Cells from a donor are transplanted to the patient after treatment. Donors for Allogeneic BMT are as under:-
· Haploidentical: Half Matched and related Donor.
· Syngeneic: Donor and Recipient are identical twins.
· Matched and Unrelated Donor (MUD)
· Umbilical Cord Blood Transplant: A Cord Blood Transplant uses cells collected from the blood of a new born’s Umbilical Cord.
A bone marrow transplant is done by transferring stem cells from one person to another. Stem cells can either be collected from the circulating cells in the blood (the peripheral system) or from the bone marrow.
· Peripheral blood stem cells. Peripheral blood stem cells (PBSCs) are collected by apheresis, a process in which the donor is connected to a special cell separation machine via a needle inserted in donor’s veins. Blood is taken from one vein and is circulated though the machine which removes the stem cells and returns the remaining blood and plasma back to the donor through another needle inserted into the opposite arm. Several sessions may be required to collect enough stem cells to ensure a chance of successful engraftment in the recipient.
Medication shall be given to the donor for about 4 days prior to apheresis that will stimulate the bone marrow to increase production of new stem cells. These new stem cells will be released from the marrow and into the circulating or peripheral blood system; from there they can be collected during apheresis.
· Bone marrow harvest. Bone marrow harvesting involves collecting stem cells with a needle placed into the soft center of the bone, the marrow. Most sites used for bone marrow harvesting are located in the hip bones and the sternum. The procedure takes place in the operating room. The donor will be anesthetized during the harvest and will not feel the needle. During recovery, the donor may experience some pain in the areas where the needle was inserted.
If the donor is the person himself or herself (patient), it is called an autologous bone marrow transplant. If an autologous transplant is planned, previously collected stem cells, from either peripheral (apheresis) or bone marrow harvest, are counted, screened, and infused into the patient.
Stage 1: Evaluating the patients for BMT (Work up)
Duration: 14 - 30 days
Patient undergoes complete medical check-up to evaluate suitability to go through the BMT procedure. This involves the following:
· Blood Tests
· Chest X- ray and CT Scans
· Tests to assess the condition of heart and lungs
· Bone Marrow Tests
Patients are counselled in detail about the procedure, complications, chances of success, cost and the possible length of stay in the hospital. Patients are encouraged to go through the educational material/brochure and discuss any queries or doubts that they have.
Insertion of Hickman Line:
The process of BMT is not a single surgical operation like liver or kidney transplantation. In fact, it is an elaborate process of creating space in the patient’s marrow, infusing the blood stem cells and supporting the patient during the next 2-3 weeks, until the donor stem cells give rise to new blood cells.
During this entire process, the patient requires continuous and repeated administration of fluids, IV medicines, blood products and IV nutrition. This is facilitated by inserting a long-term indwelling central venous catheter which is tunnelled under the skin. This is named after its innovator as HICKMAN LINE. This line, if taken care of properly can last for many months.
If the going is smooth and no complications are encountered or anticipated, we remove this catheter, 3 months after BMT.
Stage 2: Preparing the patient for BMT (conditioning)
Duration: 2 - 10 days
High doses of chemotherapy or radiotherapy are given to destroy the diseased marrow and destroy the cancer anywhere else in the body. As a result, the bone marrow gets damaged. This is required to create space for new blood stem cell and also to suppress the patient’s own immune system (in case of allogeneic transplant), so that the donor blood stem cells are not rejected.
The actual process of transplantation
The transplant procedure is actually fairly simple, the stem cells or bone marrow cells to be transplanted are given through the Hickman line.
The procedure is just like getting a blood transfusion, except the following precautions are taken care of:
· Just before the infusion of the new bone marrow, the patient may be given medication to avoid any allergic reactions.
· A monitor is used to check breathing, heart rate and blood pressure during the procedure. The nurse monitors closely throughout the infusion of stem cells or bone marrow.
· A doctor is available in the unit and checks the patients periodically. Medications may be given to deal with problems that may arise, such as high blood pressure or a fast heart rate.
Stage 3: Pre-engraftment (before the transplanted blood stem cells start working)
Duration: 2 - 3 weeks
After high dose chemo-radiotherapy the blood stem cells are destroyed and normal blood cells are not produced. The patients need to be kept in a clean room within the BMT unit in strict isolation during this time. They also need a lot of blood and platelet transfusion. Most patients get serious infections during this period and need treatment with antibiotics.
Stage 4: Post-engraftment (after the transplanted blood stem cells start working)