Bone marrow is a soft fatty tissue found inside the bones. It produces blood cells (red blood cells, platelets and white blood cells). When the patient develops disease of the blood cells (anemia, leukemia, or lymphoma) or when cancer treatment like chemotherapy and radiation therapy damages or destroys the bone marrow, a transplant with healthy bone marrow is needed to save the patient's life. Patients also need bone marrow transplants when they have dangerously low white blood cells (which are needed to fight infection) as a result of cancer treatment.
What the Procedure Involves:
First a donor is identified through a process called HLA tissue typing. The best match is a twin, a brother or sister and finally an unrelated person. The patient is given a high dose of chemotherapy to destroy all the bone marrow in the body. Bone marrow istaken from the donor in the operating room under general anesthesia. Some of patient's bone marrow is removed from the top of the hipbone (iliac crest). The bone marrow is filtered, treated, and transplanted immediately or frozen and stored for later use. The donor's bone marrow is transfused into the patient through a vein (IV line) and is naturally transported back into the bone cavities where it grows quickly to replace the old bone marrow. This is called allogeneic bone marrow transplant.
In a newer version of the therapy, called antilogous bone marrow transplant, the bone marrow is taken from the patient himself, treated with drugs to kill any cancer cells and frozen. This is later thawed and transfused back into the patient after initial high dose
The hospitalization period for bone marrow transplant is from 4 to 6 weeks, during which time the patient is isolated and strictly monitored because of the increased risk of infection. The legs in particular are moved often to reduce the risk of deep venous thrombosis. Besides the usual risks associated with any kind or surgery, such as reaction to medication and problems of breathing due to the effect of anesthesia, bleeding and infection during surgery itself, there are additional risks associated with bone marrowtransplants. The major problem with allergenic transplants is graft versus host disease. This is the opposite of graft rejection seen in other organ transplants where the body rejects the organ as a foreign body. In this case, the transplanted bone marrow attacks the host cells as though they were foreign organisms and drugs to suppress the immune system (immunosuppressive medications) must be taken indefinitely, weakening the body's ability to fight infections.
The patient will require attentive follow-up care for 2 to 3 months after discharge from the hospital. It may take 6 months to a year for the immune system to fully recover from this procedure. Relatively normal activities can be resumed as soon as the patient feels well enough and after consulting with the doctor. However, vigorous physical activities should be avoided.
Another promising development is called peripheral blood stem cell transplantation. In this, stem cells (the precursor blood cells from which all blood cells develop) are removed from the patient before treatment and returned after chemotherapy or may be received from a donor.
Bone marrow transplant patients are usually treated in highly specialized centers and the patient stays in a special nursing unit to limit exposure to infections. In India, bone marrow transplant is offered only at a few centers, Tata Memorial Hospital, Mumbai, All India Institute of Medical Sciences, New Delhi and Christian Medical College, Vellore.