Leukemia Bone Marrow Transplant

2010-12-08

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Leukemia is a cancer of the bone marrow and blood. This form of cancer affects hematopoietic stem cells (cells which give rise to the components of blood). There are a number of different types of leukemia, dependent on which particular cell line is affected and the aggressiveness of the condition.[1] Acute leukemias tend to develop very quickly, whereas chronic leukemias progress much more slowly. The recommended treatment depends on the type of leukemia, but leukemia bone marrow transplant following a course of intensive chemotherapy is often the most appropriate course of action for many types of leukemia.

Leukemic Cells from a Patient with AML

What is the Importance of Bone Marrow in Leukemia?

Bone marrow contains hematopoietic stem cells which are capable of giving rise to the components of blood. These include red blood cells for transporting oxygen, white blood cells for fighting infection and platelets which are involved in clotting.[2] In leukemia, some bone marrow stem cells become abnormal and are no longer capable of generating functional blood components. These abnormal cells are sometimes referred to as leukemic stem cells, and they accumulate in the bone marrow and the blood, resulting in less space being available for normal cells.[3]

Why Use Bone Marrow Stem Cell Transplants to Treat Leukemia?

In many cases of leukemia, leukemic stem cells must be removed by aggressive chemotherapy. However, to ensure this treatment is effective in destroying all the cancerous cells, healthy bone marrow tissue may also be damaged. In order for the patient to make a rapid recovery, bone marrow stem cells are needed to start replenishing the supply of cells and other blood components, and to replace the diseased or damaged bone marrow.[4]

How Are the Cells Transplanted?

A bone marrow transplant is not a surgical procedure. The stem cells to be grafted are simply administered intravenously directly into the patient’s blood stream. If successful, the bone marrow stem cells will then migrate to the cavities of the large bones of the body, where they will begin to generate new blood components.[5]

Sources of Stem Cells for Transplant

Almost all bone marrow transplants in the treatment of leukemia originate from a donor, and are so-called allogeneic transplants. The donor’s bone marrow type must match the genetic make-up of the recipient’s bone marrow as closely as possible in order to avoid rejection, so relatives are often able to act as donors. The bone marrow harvest takes place under general anesthetic, and involves inserting a needle into a cavity of the rear hip bone.[6] This procedure involves very little risk and minimal discomfort.

Most bone marrow transplants originate from adult donors, but increasingly cord blood stem cells are being use as there is no risk to the donor and the cells are immediately available, also the donor and the recipient need not be such a close immunological match.[7]

Risks and Side Effects of Bone Marrow Transplantation

The chance of a bone marrow transplant proving an effective therapy depends on the condition being treated. Very rarely, the grafted cells may fail to migrate to the bone marrow in which case a further graft may be needed. Possible side effects include a risk of infection, anemia, bleeding due to lack of platelets and eating problems related to nausea or mucositis.[8] A potentially serious complication is graft versus host disease (GVHD) in which the donor white blood cells begin to attack the patient’s own healthy cells, but medication is available to help prevent this.