Allogenic Bone Marrow Transplant

Allogenic bone marrow transplantation is a procedure in which a patient receives stem cells from a matched donor (genetically similar but not identical), to suppress the disease and restore the immune system. The stem cells found in umbilical cord blood are less mature, and have the potential to differentiate into various types of cells. Donor registries can be used to find the appropriate match, through tissue typing. This is unlike an autologous stem cell transplant;in which the stem cells are used from the patient's own body.

The donor`s healthy stem cells are used to replace the patient’s morbid ones (which have been damaged by disease) by giving high doses of chemotherapy and radiotherapy used to treat the underlying disease. The cells of the donor’s immune system (white blood cells) are transplanted along with the donor’s stem cells with the hope that these cells will also attack and destroy all traces of the underlying disease.

Allogeneic transplants can offer the best chance to cure a number of blood and bone marrow cancers, are complex procedures and carry significant risks. The complexities and risks in such transplants are increased with a mismatched donor transplant.

It is important to realize that theseprocesses are often long and complex. A transplant involves a lot of preparation and a lot of aftercare. The process of a stem cell transplant can be divided into these different stages:

• planning for your transplant
• conditioning therapy
• The transplant process
• Engraftment
• Post-transplant Complications
• Recovery

Procedure

Before an allogeneic stem cell transplant, a conditioning regime is initiated. This process involves administering high-dose chemotherapy alone or with radiation therapy to destroy as many cancer cells as possible. Conditioning therapy is used to suppress the immune system to reduce the risk of it rejecting the donor stem cells. The blood counts initially drop dramatically in the week following conditioning therapy. During this time, the patient is more at risk of infections (due to the lack of infection-fighting white blood cells) and bleeding (due to a lack of platelets). For the same, antibiotics and platelet transfusions aregiven. Red blood cell transfusions are given when hemoglobin levels are too low. During this time, the common side-effects of chemotherapy and radiotherapy may be experienced such as nausea, vomiting, mucositis (sore mouth) and bowel problems (diarrhea).

Once this preparative regime is complete, the transplant procedure is initiated, typically about two days after the intensive treatment is complete. The donated stem cells are transfused intravenously for about an hour. The stem cells then travel from bloodstream to the bone marrow and begin to produce new blood cells in a process known as engraftment. Once the blood stem cells have engrafted, blood counts start to rise. Generally, close monitoring and supervision is maintained by the doctors during the early weeks of your recovery. The transplant restores the supply of normal cells that have been destroyed.Post-transplant, the doctor will advise a number of tests to make sure that the vital organs (heart, lungs, liver and kidneys) are functioning properly.Although the stem cells have engrafted, the body would require sufficient time (approximately six months)to recover to a normal level of functioning. Some side effects persist for months and occasionally years after the transplant.

Complications

Sometimes serious complication of allogeneic transplants called graft-versus-host disease (GVHD) may be experienced, which is an immune reaction whereby cells from the donor’s immune system recognize the patient’s body as foreign and attack it. GVHD can vary in severity and the extent to which it causes problems in the body. Acute GVHD is usually managed with steroids to reduce the complication and further suppression of the new immune system. Other complications or side effects include risk of infection, fertility problems, earlier than expected menopause, losing immunity of prior vaccinations, veno-occlusive disease of the liver, leukemic relapse, and graft failure. Despite all these complications, allogeneic BMT remains a highly successful therapeutic procedure associated with a 20% to 90% long-term disease-free survival in a variety of patients.