Bone marrow transplantation
Bone marrow transplantation is a medical procedure designed to treat severe dysfunctions of the immune and blood-forming systems, often due to conditions such as leukemia, cancer, and hereditary diseases. This procedure is typically considered when other treatment options have failed, especially for patients under fifty, with children having the highest success rates. The transplantation involves extracting bone marrow from either the patient (autologous transplantation) or a compatible donor (allogeneic transplantation). The harvested marrow, rich in stem cells, is processed and stored until the patient is ready for the procedure, which usually follows intensive chemotherapy or radiation to eliminate malignant cells.
The procedure carries risks, including complications such as graft-versus-host disease (GVHD), where the donor's immune cells attack the recipient's body. Finding a suitable donor is a crucial challenge, as the best matches are often siblings, but even then, the likelihood of a good match is only about 25%. The success rates of transplants can vary widely, from 10 to 90 percent, depending on various factors, including the patient's condition and donor compatibility. Despite its complexities and risks, advancements in research and donor recruitment continue to improve the outcomes of bone marrow transplants, paving the way for more effective treatments in the future.
Bone marrow transplantation
Anatomy or system affected: Back, blood, bones, immune system, musculoskeletal system
Definition: The replacement of diseased or inadequate bone marrow with healthy marrow.
Indications and Procedures
Bone marrow transplantation is used when the immune and blood-forming systems of the body are malfunctioning or have been severely damaged. Without adequate white blood cells, a person will soon die from infection. Transplantation is an attempt to cure or arrest diseases such as leukemia, cancer, and sickle cell disease and conditions such as brain tumors and hereditary diseases. Bone marrow transplantation is used when all other methods of treatment have failed. The procedure is usually performed on patients who are younger than fifty years old, with the greatest success rates found in children.

Before the procedure can be performed, a suitable donor must be found. The donor can be the patient (autologous transplantation) or someone else (allogeneic transplantation). Once the donor is identified, the bone marrow is harvested. This procedure is usually done under general anesthesia and takes one to two hours. A needle is inserted in the hip, and marrow is sucked out from different locations in the pelvic bone. Approximately one to three pints of marrow are taken. The donor usually stays overnight in the hospital and may be sore for one or two weeks following the operation.
The marrow, which contains the stem cells necessary to reestablish the blood-producing and immune systems of the patient, is processed and stored until the patient is prepared for the transplantation. During the hospital stay, the patient is kept in a sterile room to prevent infection. If the surgery is being performed on a cancer patient, the patient receives extensive chemotherapy and/or radiation before the donor marrow is transplanted; this action destroys any cancer cells in the patient, as well as their immune system.
The patient then receives the bone marrow transplantation in a manner similar to a blood transfusion: the donor cells are introduced through the veins and into the bloodstream. Until the transplanted cells begin to function (usually two to four weeks), the patient receives blood and platelet transfusions, as well as antibiotics to fight infection. The patient is usually discharged from the hospital in a month but must take antibiotics and antiviral medications for six months to two years after the transplantation because the recovery of the immune system is slow.
Uses and Complications
Bone marrow transplantation is a risky procedure with a success rate that ranges from 10 to 90 percent. The success of a bone marrow transplant depends on several factors, including the malignancy of the patient’s disease and the relationship, or lack of it, of the donor to the patient. One of the greatest obstacles is finding a suitable donor. The best possible match is between siblings, but even here, the probability of a correct match is only 25 percent. Unrelated donor and patient matches made with marrow from donor banks increase the risk of a mismatch.
Finding a suitable donor is imperative because of the risk of graft-versus-host disease (GVHD). GVHD occurs when the donor cells recognize the host’s body as foreign and react against it. This reaction may occur within a hundred or more days after the transplant and can vary in severity from a mild rash to the fatal destruction of tissue and organs. For correctly matched donors and recipients, the risk of life-threatening GVHD is 10 to 20 percent. For mismatched donors and recipients, the risk rises to 80 percent. In some cases, especially with leukemia and cancerous blood diseases, patients who suffer mild GVHD have an improved chance of survival because part of GVHD is a graft-versus-leukemia (GVL) effect. In these cases, the transplanted immune system acts against any remaining leukemia cells.
When the patient does not have a condition that damages the bone marrow, transplantation can be performed with their own marrow. After marrow has been collected from the patient, radiation and/or chemotherapy can be used to destroy the remaining immune system. Autologous transplantation eliminates the need to find a compatible donor and the risk of GVHD. This method can be used for treating solid tumors and has shown promise in curing brain tumors that were once considered fatal, with a success rate of 20 percent.
Bone marrow transplants are understandably stressful on top of the patient dealing with a serious illness. In April 2013, scientists at the Abramson Cancer Center of the University of Pennsylvania published a study of 300,000 bone marrow transplant recipients. According to the study, transplant recipients are at increased risk for suicide and accidental death.
Perspective and Prospects
Research on bone marrow transplantation began in the early 1950s, with the first successful transplantations performed on children in 1968. By the 1990s, more than five thousand bone marrow transplantations were being performed worldwide every year. The development of drugs that work to suppress the immune system has increased the chances of survival for these patients.
Several areas of research promise even better results in the future. A growing understanding of disease at the genetic level offers the possibility of separating unhealthy bone marrow cells from healthy ones. Methods of growing cells outside the body for use in transplantation are being developed. Progress has also been made in increasing the donor pool. National and international programs actively seek potential donors. Healthy people can also store their own bone marrow for a possible need in the future through umbilical cord blood banking, which is one of the most promising potential sources of donor bone marrow because it is rich in stem cells. Transplants using umbilical cord blood were first used in 1989 and have proven very successful. Established in the twenty-first century, umbilical cord blood banks greatly increase the quantity of available donor marrow.
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