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A pediatric bone marrow transplant (BMT) is a medical procedure in which blood and bone marrow is transplanted into a pediatric patient. Bone marrow is the fatty tissue inside bones that produces stem cells. In turn, these stem cells produce platelets, white blood cells, and red blood cells. These blood cells are vital to fighting disease, preventing bleeds, getting oxygen and nourishment to cells throughout the body, and removing carbon dioxide from the cells in the body. If a disease corrupts the functioning of a child’s bone marrow, or bone marrow is depleted due to a medical treatment, it can have devastating effects on the body. In these cases, a pediatric bone marrow transplant is often the best option.
Several conditions can necessitate a pediatric bone marrow transplant. Some of these include leukemia, ovarian cancer, kidney cancer, aplastic anemia, lymphomas, brain tumors, neuroblastomas, rhabdomyosarcomas, sickle cell disease, Wiskott-Aldrich syndrome, thallasemia, Hurler's syndrome, adrenoleukodystrophy disorder, and Blackfan-Diamond anemia. BMT strives to rid the body of unhealthy marrow, usually with chemotherapy, and replace it with healthy marrow from a donor. This is a difficult procedure and is best done either early on in the disease, during remission, when the body will respond well to chemotherapy, or when the body is strong enough to take the blow of a BMT. A physician will help weigh the treatment options and recommend when and if it is the right time to consider a pediatric bone marrow transplant.
If the transplant is indicated, the patient may then begin preparing for either an autologous or allogeneic transplant. With an autologous transplant, the transplant cells are sourced from the recipient’s own body or an identical twin, if possible. An allogeneic transplant uses stem cells from another person who may or may not be related to the patient. Autologous transplants have a lower risk of rejecting the transplanted cells, but have a higher risk of relapse. To minimize the risk of the child rejecting the donated cells in allogeneic transplant, doctors prefer that the donor be related to the recipient and require that the donor has a close match to the recipient’s tissue.
Once a donor is found, the child will begin conditioning for the pediatric bone marrow transplant around ten to seven days before the procedure. Usually, conditioning includes chemotherapy, radiation, and other medical treatments to eliminate the diseased tissue in preparation for the new healthy marrow. The timing and process of harvesting this donor marrow will depend on the type of transplant. In an allogeneic transplant, the donor is anesthetized before the physician harvests the stem cells by inserting a needle into the interior of a bone, usually the hip or sternum. If the child is undergoing an autologous transplant, the marrow will be removed from the body, treated, and frozen to be transplanted after conditioning. Sometimes the stem cells are removed from the umbilical cord and placenta at birth and then stored for a later BMT.
The marrow is then administered into the child’s bloodstream through a central venous catheter. The child may experience fever, chills, pain, and rash during the transfusion. In recovery, the patient can expect to stay in the hospital for several weeks, during which time the child may suffer from bleeding, increased susceptibility to infection, emotional stress, weakness, vomiting, nausea, diarrhea, and mouth sores. The child may require blood transfusions, various medications, and a sterile environment to mitigate these side effects. Around 15 to 30 days after the pediatric bone marrow transplant, the donated marrow should undergo engraftment. This means that the stem cells have arrived in the patient’s marrow and have begun producing new blood cells.
The complications of a pediatric bone marrow transplant include infection, respiratory distress, failure of the stem cells to graft to the marrow, damage to the liver or heart, potentially life threatening respiratory problems, low red blood cells and platelets, and graft-versus-host disease (GVHD). GVHD occurs when the immune cells in the donated marrow recognizes the tissue of the recipient as foreign and reacts against it. This can be a deadly complication, so the patient will be given medications prior to the transfusion and monitored closely afterword to prevent GVHD.