Bone marrow is the soft, spongy tissue found inside bones. It contains specialist stem cells, which produce the body’s blood cells. Stem cells in bone marrow produce three important types of blood cells:
It is the stem cells that are needed in BMT.
A BMT, also called a stem cell transplant, is a special therapy for patients with certain cancers or other diseases. It involves transfusing healthy stem cells into the patient’s body to replace damaged or diseased bone marrow. A BMT may be necessary if the bone marrow stops working and doesn’t produce enough healthy stem cells.
There are different types of BMT depending on who the donor is. The different types of BMT include the following:
Stem cells are tested, typed, counted, and frozen until they are needed for a transplant. BMT has been used successfully to treat diseases such as leukemias, lymphomas, aplastic anemia, immune deficiency disorders, and some solid tumor cancers.
A BMT is needed to:
The following diseases are the ones that most commonly benefit from BMT:
However, patients experience diseases differently, and BMT may not be appropriate for everyone who suffers from these diseases.
Matching involves typing human leukocyte antigen (HLA) tissue. The antigens on the surface of these special white blood cells determine the genetic makeup of a person’s immune system. There are at least 100 HLA antigens; however, it is believed that there are a few major antigens that determine whether a donor and recipient match. The others are considered "minor" and their effect on a successful transplant is not as well-defined.
The more the antigens match, the better the engraftment of donated marrow. Engraftment of the stem cells occurs when the donated cells make their way to the marrow and begin producing new blood cells.
Most of the genes that "code" for the human immune system are on one chromosome. Since we only have two of each chromosome, one we received from each of our parents, a full sibling of a patient in need of a transplant has a one in four chance of having gotten the same set of chromosomes and being a "full match" for transplantation.
An extensive evaluation is completed by the BMT team. The decision for you to undergo a BMT will be based on many factors, including the following:
A BMT involves several risks, some potentially fatal. The complications depend on many factors, including the type of disease or condition, the type of transplant, and the age and health of the person.
Some people experience few problems with a transplant, while others may develop serious complications that may require hospitalization. The following are some complications that may occur with a BMT. However, each individual may experience symptoms differently. These complications may also occur alone, or in combination:
Preparation for the recipient: A patient who has to undergo a BMT will be:
For an allogeneic transplant, finding a matching donor can be a long process, especially if a sibling match is not available. One can also look up national and international registries for registered voluntary marrow donors. A bone marrow search involves searching these registries for donors whose blood most closely resembles or matches the individual needing the transplant.
A healthy, matching donor is needed for carrying out a BMT. A donor can be self, sibling, parent or relative, non-related person, or umbilical cord from a related or non-related person. Some family members may be typed if a donor is not available immediately. A potential donor who matches the genetic type of the patient needing a transplant will have to undergo a series of tests related to his or her health, exposure to viruses, and genetic analysis will be done to determine the extent of the match. The donor will be given instructions on how a bone marrow donation will be made.
Once a match for a patient needing a BMT is found, then stem cells will be collected either from the circulating cells in the blood (the peripheral system) or from the bone marrow harvest.
If the donor is the person himself or herself, previously collected and frozen stem cells, from either peripheral (apheresis) or harvest, are counted, screened, and ready to infuse.
The preparations for a BMT vary depending on the type of transplant, the disease requiring transplant, and your tolerance for certain medications. Consider the following:
A conditioning process prepares your body for the transplant. Most often, high doses of chemotherapy and/or radiation are included in the preparations. This is done to
After the chemotherapy and/or radiation is administered, the stem cell transplant can take place. On the day of your transplant, called day zero, the stem cells are given through the central venous catheter into the bloodstream. It is not a surgical procedure to place the marrow into the bone, but is similar to receiving a blood transfusion. The stem cells make their way into the bone marrow and begin reproducing and growing new, healthy blood cells. You are awake during the procedure.
During infusion of bone marrow, the patient may experience the following:
Once the new stem cells enter your body, they travel to your bone marrow. In time, they multiply and begin to make new, healthy blood cells. This is called engraftment. It usually takes several weeks before the number of blood cells in your body starts to return to normal. In some people, it may take longer.
After the transplant, supportive care is given to prevent and treat infections, side effects of treatments, and complications. This includes frequent blood tests, close monitoring of vital signs and strict measurement of fluid input and output. You may need medicine to manage complications, such as nausea and diarrhea.
Blood counts will be checked frequently during the days following transplant to evaluate initiation and progress of engraftment. Platelets are generally the last blood cell to recover. You may need periodic transfusions of red blood cells and platelets until your bone marrow begins producing enough of those cells on its own.
Engraftment can be delayed because of infection, medications, low donated stem cell count, or graft failure. Although the new bone marrow may begin making cells in the first 30 days following transplant, it may take months, even years, for the entire immune system to fully recover. After infusion, you may spend several weeks in the hospital.
After leaving the hospital, the recovery process continues for several months or longer, during which time the patient cannot return to work or many previously enjoyed activities. The patient must also make frequent follow-up visits to the hospital or doctor’s office. Prognosis greatly depends on the following:
A BMT may completely or partially cure your illness. If the transplant is a success, you can go back to most of your normal activities as soon as you feel well enough. Usually it takes up to one year to recover fully.
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