Bone Marrow Transplantation and Peripheral Blood Stem Cell Transplantation: Questions and Answers
6. How is bone marrow obtained for transplantation?
The stem cells used in BMT come from the liquid center of the bone, called the marrow. In general, the procedure for obtaining bone marrow, which is called "harvesting, " is similar for all three types of BMTs (autologous, syngeneic, and allogeneic). The donor is given either general anesthesia, which puts the person to sleep during the procedure, or regional anesthesia, which causes loss of feeling below the waist. Needles are inserted through the skin over the pelvic (hip) bone or, in rare cases, the sternum (breastbone), and into the bone marrow to draw the marrow out of the bone. Harvesting the marrow takes about an hour.
The harvested bone marrow is then processed to remove blood and bone fragments. Harvested bone marrow can be combined with a preservative and frozen to keep the stem cells alive until they are needed. This technique is known as cryopreservation. Stem cells can be cryopreserved for many years.
7. How are PBSCs obtained for transplantation?
The stem cells used in PBSCT come from the bloodstream. A process called apheresis or leukapheresis is used to obtain PBSCs for transplantation. For 4 or 5 days before apheresis, the donor may be given a medication to increase the number of stem cells released into the bloodstream. In apheresis, blood is removed through a large vein in the arm or a central venous catheter (a flexible tube that is placed in a large vein in the neck, chest, or groin area). The blood goes through a machine that removes the stem cells. The blood is then returned to the donor and the collected cells are stored. Apheresis typically takes 4 to 6 hours. The stem cells are then frozen until they are given to the recipient.
8. How are umbilical cord stem cells obtained for transplantation?
Stem cells also may be retrieved from umbilical cord blood. For this to occur, the mother must contact a cord blood bank before the baby's birth. The cord blood bank may request that she complete a questionnaire and give a small blood sample.
Cord blood banks may be public or commercial. Public cord blood banks accept donations of cord blood and may provide the donated stem cells to another matched individual in their network. In contrast, commercial cord blood banks will store the cord blood for the family, in case it is needed later for the child or another family member.
After the baby is born and the umbilical cord has been cut, blood is retrieved from the umbilical cord and placenta. This process poses minimal health risk to the mother or the child. If the mother agrees, the umbilical cord blood is processed and frozen for storage by the cord blood bank. Only a small amount of blood can be retrieved from the umbilical cord and placenta, so the collected stem cells are typically used for children or small adults.