Bone marrow transplant 1
This blog entry begins a series of entries related to the class of stem cell therapy typically referred to as bone marrow transplant or stem cell rescue. The information here is taken, with only minor changes, from CancerHealthOnline (http://cancer.healthcentersonline.com/bloodbonecancer/bonemarrowtransplants.cfm )
Bone marrow transplants have been used for over 40 years, primarily to treat patients with cancer. Bone marrow is the soft and spongy material found inside a person's bones. In the 1960s, researchers discovered that bone marrow contains at least two kinds of stem cells.  One population, called hematopoietic stem cells (HSC), forms all the types of blood cells in the body:
- Additional hematopoietic stem cells.
- White blood cells that protect the body from diseases, including potentially life–threatening infections.
- Red blood cells that carry oxygen to all parts of the body and take carbon dioxide from the cells back to the lungs to be expelled from the body.
- Platelets that help clot blood to keep patient from excessive bleeding or bruising.
While most of the body’s hematopoietic cells are found in bone marrow, some appear in the bloodstream. These are called peripheral blood stem cells (PBSC). In addition, blood in the umbilical cord contains heamtopoietic stem cells. All of these sources of stem cells are used in bone marrow transplants.
Bone marrow transplants are performed in cancer patients for two main reasons:
- To support other cancer–fighting therapies. High doses of chemotherapy or radiation therapy are often used to target and kill cancer cells. However, these treatments have the undesirable side effect of killing other normal cells. Bone marrow cells generally are more vulnerable to these destructive effects than any other cells in the body.
- To directly attack and kill cancer cells. Transplanted bone marrow can recognize cancer cells that exist in a patient as being abnormal, and will thus attack and try to destroy the cancer cells.
The three types of transplantation are
- Autologous transplant. A patient's own stem cells are used (removed and stored ahead of time)
- Syngeneic transplant. Stem cells from an identical twin are used. Because identical twins share the same genes, there is no risk of rejection in this form of transplant.
- Allogeneic transplant. Stem cells come from someone other than the patient or an identical twin. This can be a family member, or someone unrelated to the patient. The greatest potential for immune system problems (rejection, graft-vs-host) comes from this form of transplant.
Bone marrow transplants are most often used in the treatment of leukemia or lymphoma, and are most effective when these diseases are in remission. Other cancers that may require bone marrow transplants included neuroblastoma and multiple myeloma.
Next: Preparation for BMT
Marie Godfrey, PhD