Stem cell transplantation, otherwise known as bone marrow transplantation, is the infusion of healthy stem cells into the body to stimulate new bone marrow growth. Stem cells are vital to a person’s ability to fight infection, and stem cell transplants are performed on children whose stem cells have been damaged by disease or invasive treatments for cancer, such as chemotherapy and/or radiation therapy.
Stem cell transplants can be used to treat many conditions affecting children and teens, including leukemia, lymphoma, aplastic anemia and thalassemia. There are two types: Autologous transplants, in which the patient’s own stem cells are collected, stored at a special laboratory and re-introduced into the patient’s system intravenously, and allogeneic transplants, in which stem cells are collected from a tissue-matched donor (a sibling, an unrelated donor, or umbilical cord blood) and delivered intravenously.
Here’s what to expect during a pediatric stem cell transplant.
Conditioning therapy refers to the high-dose chemotherapy and/or radiation that children receive before their stem cell infusion. The day a child receives the bone marrow or stem cells is called Day Zero (Day 0). The days prior to Day 0 are the days that a patient receives the conditioning therapy.
There are several goals of conditioning therapy: To kill cancer cells in the body in patients with a malignant disorder, and to kill the normal cells in the marrow cavities of the bones so the new marrow will have room to grow. If the child is receiving cells from another person, conditioning therapy has a third goal: To suppress the child’s immune system so it will not reject the donor’s cells.
Day 0: Stem Cell Infusion
Day 0 is the day the stem cells are infused through the child’s central venous line.
Expected Side Effects
After Day 0, patients may begin to have some of the expected side effects of the conditioning therapy such as nausea, vomiting, diarrhea and mouth sores.
Infections After Transplant
Stem cell transplantation patients are at high risk for infections because the immune system is suppressed from the conditioning therapy. Patients who receive stem cells from another person have an additional risk for infection since they take medications that suppress the new immune system. Patients need these immunosuppressive medicines in order to help prevent graft-versus-host disease (GVHD).
After the marrow has been infused, the number of white blood cells and neutrophils, a certain type of white blood cell, increase over the next two to four weeks. Engraftment occurs when the stem cell graft is making enough neutrophils to offer some protection against bacterial infections.
If your child receives stem cells from someone else, there is a risk of graft-versus-host disease (GVHD). GVHD may occur before or after stem cell engraftment. It is caused when the donor’s (graft) T lymphocytes, a type of white blood cell, react against the cells of the patient (host). Therefore, the condition is called graft (donor)-versus-host (patient) disease. The patient is most likely to show the effects of GVHD in the skin, the gastrointestinal tract (digestive system) and the liver. In general, acute GVHD occurs before Day +100 and chronic GVHD occurs after Day +100.
Other Side Effects
The conditioning therapy and medications used during transplant may cause other side effects and toxicities. At Dana-Farber/Boston Children’s Cancer and Blood Disorders Center, these are discussed during the initial consent meeting. Doctors and nurses are also able to explain these problems and the recommended treatments if they occur. Blood tests, X-rays, CAT scans, MRI scans, ultrasounds or biopsies (tissue samples) of certain tissues may help in the diagnosis of such problems.
A child may be discharged after engraftment has occurred. He or she must also be medically stable and able to take the required medications.
Restrictions after Discharge
Autologous (self) transplant patients should not attend school or visit other public indoor places for six months after transplant. Allogeneic (related and unrelated donor) transplant patients should not attend school or visit indoor public places for nine to 12 months after transplant, depending on the patient’s status.