Leukemia Treatment Stem Cell Transplant

Stem cell transplants are a possible treatment for leukemia. During stem cell therapy, a patient receives chemotherapy to kill existing leukemia stem cells. Once the bone marrow is dead, healthy stem cells are introduced. If successful, donor stem cells replace leukemia stem cells and begin producing healthy blood cells.

Reasons for Stem Cell Therapy

Stem cell therapy for leukemia is a serious procedure, and can cause significant side effects. The risks of stem cell transplants must be weighed against the benefits. However, successful stem cell transplants result in leukemia remission.

Stem cell transplants make aggressive leukemia treatment with very high chemotherapy doses possible. Normally, high doses of chemotherapy would prove fatal without stem cell therapy. This is because the medication kills leukemia cells, as well as existing bone marrow, making the production of new blood cells impossible. The introduction of donor stem cells makes it possible to survive intense chemotherapy.

Immune factors produced by the donor stem cells also help fight leukemia. As the new stem cells produce white blood cells and immune factors, the introduced cells help destroy any leukemia cells that might have survived chemotherapy treatment.

Types of Stem Cell Transplants

There are two general types of stem cell transplants:

  • Allogenic stem cell transplants use stem cells from donors, either family members or unrelated, whose stem cells match the patient’s.
  • Autologous stem cell transplants use stem cells from the patient.

Harvesting Stem Cells

Healthy stem cells can be harvested in different ways. A doctor may insert a long needle to retrieve bone marrow stem cells from the donor’s pelvis or other bone. This procedure requires anesthetic and multiple needle aspirations.

Doctors may also collect stem cells through peripheral blood stem cell transplantation. Using a process called apheresis or leukapheresis, a doctor removes blood through a donor’s large vein. A machine filters out the blood’s stem cells and returns the blood to the donor. Although apheresis doesn’t yield as many stem cells as bone marrow harvesting, the procedure is less invasive. Donors may take medication for four or five days prior to the procedure, in order to increase stem cell count.

Umbilical cord blood may also provide stem cells. Parents may donate the blood to a public donor or store it for future use.

Stem Cell Transplant - Leukemia Treatment

Stem Cell Therapy for Leukemia Treatment

Before receiving stem cell therapy, a patient undergoes conditioning. During this period, a patient receives high doses of chemotherapy, sometimes supplemented with radiation therapy. The goal is to both kill existing leukemia stem cells and impair the immune system, so the body does not reject introduced stem cells.

Stem cells are introduced through a catheter in a large vein. Once in the bloodstream, healthy stem cells migrate to the bone marrow, where they begin to produce new blood cells. This process, called engraftment, can take up to a month to begin, during which time the patient is carefully monitored. Stem cell transplants take up to a year to restore the blood count and immune system to normal levels.

Complications of Stem Cell Transplants

Stem cell transplants are a complex treatment for leukemia. Complications can be fatal. Donated stem cells may fail to graft in the bone marrow. Newly introduced stem cells may also mistake host body as a threat, causing organ damage. High doses of chemotherapy raise the risk of secondary cancer developing in the future.

Despite the risk of complications, the benefits of stem cell therapy often outweigh the risks, especially when other treatment for leukemia fails.

Resources

American Cancer Society. (2009). Types of stem cell transplants. Retrieved March 31, 2010, from http://www.cancer.org/docroot/ETO/content/ETO_1_4X_Stem_Cell_Transplant_Basics.asp.

Mayo Clinic. (2008). Stem cell transplant. Retrieved March 31, 2010, from http://www.mayoclinic.com/health/stem-cell-transplant/MY00089.

National Cancer Institute. (2008). Bone marrow transplantation and peripheral blood stem cell transportation. Retrieved March 31, 2010, from http://www.cancer.gov/cancertopics/factsheet/Therapy/bone-marrow-transplant.