What is a bone marrow transplant?

Bone marrow transplant (BMT) is a special therapy for patients with certain cancers or other diseases. A bone marrow transplant involves taking cells that are normally found in the bone marrow (stem cells), filtering those cells, and giving them back either to the donor (patient) or to another person. The goal of BMT is to transfuse healthy bone marrow cells into a person after their own unhealthy bone marrow has been treated to kill the abnormal cells.

Bone marrow transplant has been used successfully to treat diseases such as leukemias, lymphomas, aplastic anemia, immune deficiency disorders, and some solid tumor cancers since 1968.

What is bone marrow?

Bone marrow is the soft, spongy tissue found inside bones. It is the medium for development and storage of most of the body's blood cells.

The blood cells that produce other blood cells are called stem cells. The most primitive of the stem cells is called the pluripotent stem cell, which is different than other blood cells with regards to the following properties:

It is the stem cells that are needed in bone marrow transplant.

Why is a bone marrow transplant needed?

The goal of a bone marrow transplant is to cure many diseases and types of cancer. When the doses of chemotherapy or radiation needed to cure a cancer are so high that a person's bone marrow stem cells will be permanently damaged or destroyed by the treatment, a bone marrow transplant may be needed. Bone marrow transplants may also be needed if the bone marrow has been destroyed by a disease.

A bone marrow transplant can be used to:

The risks and benefits must be weighed in a thorough discussion with your doctor and specialists in bone marrow transplants prior to procedure.

What are some diseases that may benefit from bone marrow transplant?

The following diseases are the ones that most commonly benefit from bone marrow transplant:

However, patients experience diseases differently, and bone marrow transplant may not be appropriate for everyone who suffers from these diseases.

What are the different types of bone marrow transplants?

There are different types of bone marrow transplants depending on who the donor is. The different types of BMT include the following:

How are a donor and recipient matched?

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.

Medical research is still investigating the role all antigens play in the process of a bone marrow transplant. The more antigens that 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.

The bone marrow transplant team

The group of specialists involved in the care of patients going through transplant is often referred to as the transplant team. All individuals work together to provide the best chance for a successful transplant. The team consists of the following:

An extensive evaluation is completed by the bone marrow transplant team. The decision for you to undergo a bone marrow transplant will be based on many factors, including the following:

For a patient receiving the transplant, the following will occur in advance of the procedure:

Preparation for the donor

How are the stem cells collected?

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.

If the donor is the person himself or herself, it is called an autologous bone marrow transplant. If an autologous transplant is planned, previously collected stem cells, from either peripheral (apheresis) or harvest, are counted, screened, and ready to infuse.

The bone marrow transplant procedure

The preparations for a bone marrow transplant vary depending on the type of transplant, the disease requiring transplant, and your tolerance for certain medications. Consider the following:

The days before transplant are counted as minus days. The day of transplant is considered day zero. Engraftment and recovery following the transplant are counted as plus days. For example, a patient may enter the hospital on day -8 for preparative regimen. The day of transplant is numbered zero. Days +1, +2, etc., will follow. There are specific events, complications, and risks associated with each day before, during, and after transplant. The days are numbered to help the patient and family understand where they are in terms of risks and discharge planning.

During infusion of bone marrow, the patient may experience the following:

After infusion, the patient may:

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.

When does engraftment occur?

Engraftment of the stem cells occurs when the donated cells make their way to the marrow and begin producing new blood cells. Depending on the type of transplant and the disease being treated, engraftment usually occurs around day +15 or +30. 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.

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.

What complications and side effects may occur following BMT?

Complications may vary, depending on the following:

The following are complications that may occur with a bone marrow transplant. However, each individual may experience symptoms differently. These complications may also occur alone, or in combination:

Long-term outlook for a bone marrow transplantation

Prognosis greatly depends on the following:

As with any procedure, in bone marrow transplant the prognosis and long-term survival can vary greatly from person to person. The number of transplants being done for an increasing number of diseases, as well as ongoing medical developments, have greatly improved the outcome for bone marrow transplant in children and adults. Continuous follow-up care is essential for the patient following a bone marrow transplant. New methods to improve treatment and to decrease complications and side effects of a bone marrow transplant are continually being discovered.

More here:
Bone Marrow Transplantation | Hematology and Oncology

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