Bone marrow transplant 3

Harvesting donor stem cells

Before a transplant can occur, donor stem cells are most often harvested from the marrow—the liquid center—of the hip bone. In rare cases, the breastbone will be used. The donor is given a general anesthetic (which puts the patient to sleep) or a regional anesthetic (which numbs all feeling below the waist). A needle is inserted through the skin and into the hip bone and the stem cells are then drawn out of the bone. Approximately 100 to 200 needle punctures are needed to remove 500 to 1,000 cubic centimeters (1 to 2 pints) of marrow. This process takes about an hour.

In the donor patient, the area where the bone marrow is taken may be stiff or sore for a few days. In addition the donor may feel tired. Most donor patients are back to normal within two to three days, though other patients may take up to a month for full recovery.

Variations on the “standard” procedure

In an autologous transplant, the patient is both the donor and the recipient. After the cells have been harvested, the patient is treated with chemotherapy or radiation.

When harvesting umbilical cord stem cells, blood is obtained from the umbilical cord and placenta after the birth process is complete. If the mother consents, the umbilical cord is processed and frozen for storage by a cord blood bank. Collected stem cells are usually used only in children or small adults, as it is possible to retrieve only a limited amount of blood from the umbilical cord and placenta.

In an allogeneic transplant, marrow received from a donor who has the same ABO red blood cell type as the patient will immediately be transplanted intravenously. However, if the red blood cell types do not match, the red cells will first have to be separated and discarded.

Processing the harvested cells

Once the marrow has been harvested, it is processed to remove all blood and bone fragments.

In an autologous transplant, the cells are stored until after the patient is finished with chemotherapy or radiation therapy. The harvested bone marrow can be combined with a preservative and frozen in a technique called cryopreservation. This keeps the stem cells alive until they are needed, and allows the stem cells to be stored for many years.

Transplant recipients

Patients who are to receive donated stem cells will first undergo a course of high–dose anticancer medications or radiation treatment. The patient then receives the stem cells through an intravenous (IV) line in a procedure similar to a blood transfusion. It takes from one to five hours to complete the transplantation. 

Source: http://cancer.healthcentersonline.com/bloodbonecancer/bonemarrowtransplants4.cfm

Marie Godfrey, PhD  <!—break-->